Last summer I went to dinner at El Bulli, a Michelin three-star restaurant famous for serving some of the world's most curious food. It's a long distance from where I live, so I had to fly to Paris, then south to Barcelona. From there I drove another three hours north to a busy beach town near the French border called Roses, then turned on to a potholed road that led up a mountain - houses falling away, the stunted trees bent like old, shadowy men. On the other side was an inlet with a few boats bobbing at anchor, lights starring the water.

I followed some stone steps from a dead man's curve in the road down to the restaurant, a low-slung, whitewashed villa where I was met by the smell of consomm¿ and chocolate, rosemary and bacon, liquorice and seawater. I passed the great lit window through which El Bulli's kitchen appears as a gleaming space-age chamber. On the other side, 40 white-coated chefs moved in a silent, surreal symphony, chopping and saut¿ing and mumbling to themselves, a ghostly machine. Black-coated waiters poured in and out with trays of glowing lollipops and wobbly gelatin cubes and a plate simply dusted with coloured spices.

Amid the hurly-burly was a short, commanding man with dark, springy hair who wore old black shoes and a red wristwatch. I watched him prowl the length of one silver counter, then turn on a heel and dive in among his pastry chefs who were streaking what looked to be green paint over transparencies. He corrected the brushwork, then nosed his way to a bank of burners, took up a strainer and inspected a yellow orb of yolk that he removed from boiling water. He slipped it into his mouth, nodded his approval, then spun to a station at the head of the kitchen to point out some deficiency in what appeared to be a dollop of bright red foam.

This man's name was Ferran Adrià, and I instantly recognised him from photographs I'd seen in cooking magazines. It was said that he was opening a new culinary path, finding a new sea route, searching for India. And he was brash. He'd brazenly declared that it was over for the French chefs (in cuisine, that's a little like announcing that it's over for Jesus Christ) and that he and his food were the future. From him, it wasn't so much a boast as a truth he held to be self-evident.

It was also said that he possessed no home, no car, no television, no stove of his own. During the six months that his restaurant was open, he supposedly slept nearby in a tiny, furnitureless room. The rest of the year he lived out of hotels or at his parents' small house in the Barcelona barrio of his childhood, in the very room in which he grew up. And, like a child, he could be whimsical. Once, he flew to Brazil in response to a fax from a very rich man with only three words: I am hungry.

I'd come a long way for dinner. But my intentions were pure. Aside from all the hype about Adrià - when asked recently, five of the world's greatest chefs picked him as the greatest of all - I'd heard that his food could accomplish one simple thing: it could make you happy. So how far was too far to travel for that? And, I wondered, what in the world does happiness taste like?

I entered El Bulli and sat. No silverware on the table, no menu. I didn't ask for a thing, nor was I asked if I wanted anything. A welcome drink suddenly appeared, a pomegranate-coloured liquid that was announced as a whiskey sour. Around me were others like me, bound by hunger, expectant. Everyone had travelled some distance to be here; everyone was about to travel farther. I saw dishes jet by but couldn't name a single one. There were white spoons filled with a green jelly and topped with what seemed to be caviar; there were foams of green and yellow and pink; and there was a plate that, by my best estimation, was covered with orange worms.

The warm sea lapped just beyond the patio, and a kind of reverential hush was disturbed by the occasional tinkling of silverware and wineglasses. I noticed a woman at a nearby table. She had put something into her mouth, and now her whole body shook slightly, as if she was having a fit of hiccups. She sat with her head bowed, her shoulders moving up and down, until she looked up at the man she was with. She had tears in her eyes, and when she met his gaze, she started laughing - unafraid laughter that made him laugh too.

I noticed another man who I'd learn was an American molecular biologist. With each new course, he stood up and switched seats, claiming later that the only way the meal made sense to him was by changing his spatial relationship to the food.

Was this madness or heaven? What kind of food makes people weep or sets them moving around a table like the hands of a clock?

When my first plate arrived, I was a little frightened. I'd never been to a restaurant where a chef completely decides what you're going to eat and drink. At El Bulli, choices were left to Adrià, el jefe maximo, and the food was delivered in bits and combinations that didn't look like food at all, accompanied by instructions from the waiter: 'This is a childhood memory. Take in one bite.' Or: 'This is trout-egg tempura. Two bites, quickly.'

It came down to a question of faith. And I suddenly felt the presence of this man, Ferran Adrià, somewhere in the shadows, holding the fork in my hand, guiding it to the plate, impaling a mound of sweet-smelling tenderness that had been introduced as 'rabbit apple', and lifting it to my mouth which, despite my misgivings, had been watering in anticipation of this very moment and watered still, now that the moment was here.

If I was hoping to discover what happiness tastes like, I needed company. I'd persuaded my wife, Sara, to join me in Spain with our baby boy and a couple of friends. Carlos, smooth in a goatee and ponytail, would join me, who was Spanishless, each day with Ferran, who was Englishless, in hopes that we would make it back to toast the sunset with wine and cheese and the rest of our posse.

One night early on, while we sat drinking red wine on the balcony off our room, a man in the adjoining room came out on his balcony too. He told us he'd driven 16 hours to get here from Italy, that his brother, who owned a restaurant in Naples, was apprenticing at a famous restaurant, and that he and his own family had arrived to taste the delicacies of the great head chef who worked there.

'You're not talking about El Bulli, are you?' Carlos asked, and the man smiled.

'You've heard of it, too,' he said. 'My brother tells me that Ferran Adrià does the impossible.'

'And your brother likes working in the kitchen?'

'He's exhausted,' the man said. 'Fifteen-hour days, seven days a week. If it weren't for Adrià, he'd probably go home right now. But in 20, 30, 40 years, they're going to say Ferran Adrià was the best that ever was, and it's going to be an honour for my brother to say he chopped his vegetables.'

Ferran Adrià often speaks of moments that mark a before and an after. For most, a dozen of these eurekas in a life is a lot. For Ferran, not a day passes that he doesn't assume he's on the verge of yet another one, that the world he has made for himself will simply explode under the weight of the new one rising from it.

His very first before-and-after came in 1985, when he was 23, standing in his kitchen, staring at yet another order for partridge. How many times had he made this dish? Hundreds? Thousands?

There was nothing haute or nouvelle about the partridge dish. It was a plato typico - escabeche de perdiz, made by every chef at every restaurant in Spain. The finished product looked as if it had been electrocuted at altitude, in midflight, and then had fallen two miles to the plate, battered and charred. But on this one particular evening, Adrià found himself suddenly incapable, frozen by some internal pause button.

How to deal with this sad bird? With the sameness of every day, of making every plate again that he'd already made before, by copying, copying, copying the recipes of dead or dying French and Spanish chefs? Wasn't there something greater, some secret waiting for release in this food?

So he began to play with the bird. He plucked the wings and pinched some meat from the bones, which gave tenderly between his fingers. He peppered the meat and swirled it with vegetables, asparagus shoots and courgette and finely shaved carrots, leeks and onions at their most succulent. Then, on a whim, he tossed in some local langosta, lobster. Because it pleased him. And without another thought he sent it out to the dining room. A deconstructed partridge. No, a deconstructed, Mediterraneanised partridge. Vaya!

But the greatest surprise came when it wasn't sent back, as the faceless diner put fork to bird and bird to mouth, participated in the deconstruction and actually liked it. And with that began the revolution, the alchemy, the culinary miracles.

Adrià experimented with gazpacho, vacuuming it into a liquidless, cold dish. When people ordered gazpacho expecting gazpacho, they did a double take at what appeared before them in a bowl: a sculpture garden of beheaded tomatoes, slivers of cucumber set like juju sticks, peeled whole onions... but where was the soup?

Dervishly, pathologically, he began changing everything. One day he got to thinking about ice cream, why it's always sweet, so he set out to obliterate the sameness of ice cream. And he did, mixing cream and milk and ice, but at the last moment substituting salt for sugar. Vaya! What he tasted in his mouth felt cool and mineral, as if it had been scooped from the dark side of the moon.

Now he saw the whole world in his kitchen: the autonomous march of history repeating history, the tyranny of that repetition. Chocolate: why not add another texture, another taste to the tongue? He made some rich dark chocolate and smeared it with streaks of green wasabi that gave it a delicious burn. Bread: why not make it explode? After baking bite-sized spheres of bread, he took a syringe and infiltrated the spongy interior with warm olive oil. He saw a simple croquette and injected it with seawater. People put them in their mouths expecting the expected - a little crunch, some chew, air - and were suddenly dealing with a burst and flood, victual chaos, palatal dyslexia, a tilting universe.

Once, back in Barcelona for the winter, he bought a truckload of perfectly ripe tomatoes. He and his brother, Albert, took the tomatoes back to their workshop, where Ferran impulsively grabbed a bicycle pump. He stuck it into a tomato and began furiously pumping until it exploded. Covered in red gook, Ferran fell upon the wreckage, sifting through it, and triumphantly lifted one shard aloft. A fine, pinkish spume bubbled along the line where air had forced a fissure. He tasted it, a tomato without body - earth, salt and juice, which suddenly disappeared like sparklers. The brothers spent the afternoon blowing up tomatoes to see what more there was to discover.

It was air that created this tomato foam, but how could you make it in the kitchen? You couldn't very well have someone in a back room with a bicycle pump, could you? Also, the foam bubbled for a moment, but then flattened and vanished. Finding the key to making this foam would be like discovering a new planet.

After experimentation with an old whipped-cream canister, and with the addition of the perfect proportion of gelatin, they finally happened upon it: a tomato foam that could stand on its own! A fine, floating, airy thing they called cloud. Soon there were curry and beet clouds, strawberry and apple clouds. Once in your mouth, they bubbled, effervesced and evaporated, leaving a tingle of taste.

His foam was soon being copied in Paris, Milan and New York and made Ferran Adrià famous. But today, less than five years later, Adrià is almost dismissive of those foams, using them sparingly. 'We opened a path and now that path is open. We may not serve any foams next year. Most restaurants are museums, but not El Bulli.' I asked him what El Bulli was all about, then. He considered for a moment, then gestured at the white-coated chefs chopping like speeded-up metronomes. 'El Bulli is crazy,' he said. 'It's the drunkenness of all the new things that can be.'

One afternoon, Carlos and I took the long drive into the mountains towards El Bulli. Up there the sky came closer, the sea glittered differently. If it was treacherous to drive the hairpins and potholes, it was easier to breathe. Later, when I would ask Adrià to describe the perfect meal, he stressed that there had to be magic in arrival. That it had to be a place hard to get to or somehow earned. That the journey, more than any appetiser or cocktail, would remind you of your hunger.

Though whimsy has made Adrià famous, one soon realises that a meal at El Bulli is driven by cold logic, co-ordinated through the phalanx of chefs at their various stations. Each guest eats roughly two dozen dishes, and if the diner rises to go to the bathroom, he can break an almost sacred rhythm that Adrià feels is crucial to the meal. 'The plate is a song,' he says. 'If the harmony is too slow, the person who receives the plate isn't receiving what the chef intended. It changes everything.' His sense of time, then, guides the journey of every morsel from kitchen to mouth, and once there, he wants you to taste it as he does. And that occasionally requires spoken instruction. 'The feeling of cold and hot is very different in one bite than in two bites,' he says. 'Sometimes, two bites makes all the difference.'

Because much of what's eaten here seems without context, the rush of these dishes builds a new context in which tastes emerge with shot-glass intensity from a nebula of cool mists and jellies. The idea is that a new dish will be launched every five minutes, no more than 10 seconds after it's ready, and in those intervals between dishes, a guest will experience both sensual and psychic lift-off, to be repeated five minutes later. In theory, this makes the meal two hours long, though often people will linger a couple of hours longer at the table.

A tray crowded with goodies appeared before us, and another, and another - what Adrià calls first and second and third 'snacks' which are meant to be fun and lighten the mood before the main courses. None were recognisable.

There was dried quinoa in a paper cone, and, when I tilted it back into my mouth, the quinoa lightly pelted my tongue and echoed in my ears like a fine rain turning crunchy. There were also seaweed nougat (salty and sublime), deep-fried bits of prawn (so light they disintegrated before they could be rightly chewed), and strawberries filled with Campari (the strawberries more strawberry because of the liqueur). No sooner would one marvel cease, one of us sputtering 'What was that?', than the next bit of Martian food would arrive. It all ended in a strange, caramelised cube that I lifted with my thumb and forefinger and gently slid on to my tongue. Only after shattering it between my teeth did the object reveal itself: yogurt bursting from its candied shell in a warm, smooth flood.

Adrià shuttled between our table and his capos - the white-shirted generals running the kitchen - and an endless drift of guests who came back to meet him. There was a famous wine critic who produced a rare Japanese spice. Some fabulously rich people shook Adrià's hand and gushed, 'You don't see this every day,' and Adrià said, 'No, this is every day.' A tanned woman with very blonde hair and long legs, wearing a sheer pinafore and a light-blue bikini underneath, climbed on to a table and started taking photographs. And, for a second, everything stopped, sighed, then resumed in double-time.

'Where the hell are the tapiocas?' a capo yelled at the hunched-over chefs on the line. 'We're going to get punished here. Let's go!'

It was hard not to feel a little ridiculous, supping on delicacies while people worked at breakneck speed to get them to us. But we didn't overanalyse this because the main dishes, 14 in all, began to arrive.

Ferran Adrià feeds you things you never thought existed, let alone things you'd think to eat: a gelatin with rare molluscs trapped inside (the cool, sweet jelly parting for salty pieces of the sea, primordial and transcendent at once); tagliatelle carbonara (chicken consommé solidified and cut into thin, coppery, pasta-like strands that, once glimmering on the tongue, dissolved back into consommé that poured down the throat); cuttlefish ravioli (the cuttlefish sliced microscopically thin, then injected with coconut milk, a sweet explosion that seemed to wrap the fish in a new sea); rosemary lamb (we were told to raise sprigs of rosemary to our noses as we munched on the lamb, the smell of rosemary becoming the lamb as if the two were the same)... and it went on like this.

I will tell you: we were happy.

When I tried later to describe the meal to Sara, I couldn't find any words. But I tried.

I tried to describe one dish in particular, an amazing, complicated thing. It was monkfish liver served as a paté and, floating on top of it, a froth of soy foam. In orbit around this foie-soy structure were quasars of orange, lemon, grapefruit and, finally, what stopped me, tomato heart its oozing seeds and essence.

What I meant to tell my wife, but couldn't, was that when I ate the substance of liver and foam with some grapefruit, and then scooped the heart, naked and dripping, into my mouth, I'd felt, in all my happiness and weird, heady lightness, an undercurrent of impermanence, some creeping feeling of danger and fear. All of it in this single bite that slid down my throat. I might have grimaced as I swallowed it; I might not have. But when I looked up, I met the gaze of Ferran Adrià, who stood across the kitchen, watching, and I wondered whether he thought I didn't like what I was eating. Or whether he knew exactly what I felt.

It's as likely that he'd have ended up a car mechanic as a chef, if not for the pleasure of beer. After quitting high school and moving to Ibiza with the full intention of living the party life, Ferran took a job washing dishes to pay for his cervezas. Up until that moment he had subsisted on steak and fries.

But working in restaurants, he slowly indoctrinated himself into a multifarious world of taste, its bombast and truths. And by the time Adrià left Ibiza at 20, he had decided: he would learn everything he could about cuisine, and through cuisine he would know everything about the world. He read Escoffier and Larousse. He made the recipes of dead chefs with zealous devotion. He had a friend who was working up the coast from Barcelona at El Bulli, a two-star restaurant with a loyal if somewhat limited clientele, and in 1983 he hitched three hours north with the thought of picking up some quick money. Eighteen years later, he's still here.

Ferran is 39 now and no more than 5ft 5in in black stocking feet. He has a hairless chest with no muscles, exactly, and a bulging belly. (This vision appeared to me one day when he changed into his chef's whites without thought of anyone else in the room.) He does, in fact, possess almost nothing of his own. He never cooks for himself or friends and always eats out, except for Christmas Day, when he cooks with his brother for their parents at home.

In the kitchen, he is demanding, withering, Napoleonic. His dissatisfaction may manifest itself like a flash thunderstorm. But he's almost preternatural to watch, like Picasso captured on film, changing a strawberry to a rooster to a woman in a few brushstrokes.

When I asked him to describe the best meal he'd ever eaten, he said he erases his memories so he doesn't live for a moment he can never bring back. When I asked about his grandparents, he could recall nothing about them. 'I think my grandfather died in the Spanish Civil War,' he said. 'Ten times - 10 times I've been told, and 10 times I've forgotten. Since I didn't know him, it's as if he never existed.' When I suggested that it's a bit strange not to know the first thing about your grandfather but then to be able to quote a recipe by Escoffier from 1907, he said, 'Not at all. My life is kitchen, kitchen, kitchen.'

When I asked if it troubled him when people didn't understand the invention and game of his cuisine, he said: 'Some people come here and see God; a few come and see the devil. The truth is relative.'

The truth is relative? 'I mean that only the tongue tells the truth. History doesn't tell it, religion doesn't. All that concerns me really is what the food tastes like. I am the chef, so I have to ask: Does it amaze me? Is there a before and after? If there is, then good. Let's eat.'

'The difference between a grand chef and a magical chef,' Adrià said, as we whizzed down the mountain, 'is that a magical chef knows not just what he's eating, but how to eat.'

'And how does a magical chef eat?' Carlos asked. Adrià's eyebrows rose at that, and an 'Ahh' passed his lips. Then he grinned and said:'You are about to see.'

We had asked him to pick his favourite place for lunch in Roses. He led us down an alley that spilled into another alley that opened on to a walking street outside a place called Rafa's, a simple, traditional open-air seafood grill with wooden tables.

'There's nothing like this place,' said Adrià. When the waitress read the day's menu, when she was through reciting 20 or so items, he looked at her and said, 'Yes,' and then clarified, 'Yes, all of it. A little bit of all of it. And whatever else the chef has.' She looked over her shoulder at Rafa, who nodded slightly and winked. And then the dishes came, each plato reflecting the way food has been served in Catalonia for hundreds of years. Tomatoes slathered on peasant bread. Sliced prosciutto on a plate. Succulent anchovies, lightly peppered, in olive oil. A small mountain of tallarines - tiny, buttery clams that we pried from their shells with our tongues, the empty shells piling like fantastic, ancient currency.

The act of eating was a full-on, full-contact orgy. Adrià's mouth, with its thin, quick lips and athletic tongue, worked frenetically. At times, he didn't just eat the food, he wore it. He took the fresh prosciutto, fine, bright prosciutto that smelled like... well, like sex... and rubbed it on his upper lip (the same as sniffing wine, he said, or eating lamb with a sprig of rosemary beneath your nose). His fingers were soon bathed in olive oil and flecked with pepper, dancing quickly from plate to plate. Platos came and went. Crustaceans arrived, various shimmering shades of orange, pink and purple, just scooped from boiling water, with waggling antennae. Adrià picked up a prawn the length of his hand. Its shell was covered on the outside with small white eggs (a prawn that I would have studiously avoided), and he began to lick the eggs with such ferocity that I decided I must have been missing something.

Particle by particle, cell by cell, he imbibed and inhaled and ingested until particle by particle and cell by cell he seemed changed by the food itself. Even when he sipped his cold beer, it was as if he were gulping from a chalice. Now he held his prawn before me, its creepy black eyes staring into mine, and asked what it looked like. 'It's intimidating, it's scary, it's prehistoric,' Adrià said. 'But in this context, it's normal. For generations, we've been eating prawns. If tomorrow someone puts a spider on the plate, then everyone's going to say it's crazy. But I don't see the difference. For you to understand what the ocean is, you have to suck this...'

He tore the head of the prawn from its carapace and held it in the space between us. 'If I can describe in one word the taste of the sea, it's sucking the head of this prawn. At home, my parents sucked the head. I tasted it and comprehended it. Just suck it.'

He took the head, put the open end to his lips, and crushed the shell until everything in it (brain and viscera, bits of meat and shell) had been expelled into his mouth, caramel-coloured liquid dribbling down his chin. He savoured it for a long moment, his eyes closed, and he seemed to have reached some kind of ecstasy. He went on. 'In a restaurant like this, we can eat the head. Spanish people find it provocative. They have an affection for it,' he said. 'At El Bulli, no, people are not prepared to eat the head. It's not permitted in high cuisine.' He took another prawn in his hand, pulled off the head, and crushed it. This time the caramel-coloured liquid pooled on the plate before him.

'But if I pour this over food in my kitchen, I've changed the context. I can do this and people will eat it. People will eat it and taste the Mediterranean.' He sat back for a moment, considered. Then he leaned forward, swiped a finger through the puddle of prawn nectar, brought it to his mouth and licked it.

'Magico,' he said.

El Bulli (00 34 972 150 457; www.elbulli.com)

Ferran Adrià's sweet purèe of vanilla potato

For the purèe:

Serves 4
200g potatoes (to mash)
130g butter (room temperature)
50g single cream
40g icing sugar
1 vanilla pod
Maldon salt
For the egg glaze:
1 egg yolk
12g hot water
1g of icing sugar
Extras:
4 vanilla pods

Peel the potatoes and cut them into pieces. Put them in a saucepan of cold water and cook over a medium heat for about 20 minutes, then drain. Keep pushing the potatoes through a sieve until you have a fine purèe. Add the cream and soft butter bit by bit, working them into the purèe.

Open the vanilla pods lengthways and, using the point of a knife, scrape out all the seeds. Add the icing sugar and vanilla seeds to the purËe and continue working them in.

Put the yolk in a metal bowl, held close to a flame but not over it, and mix until it turns white. Then add the icing sugar and continue to mix. Little by little, add the hot water .

Place a spoonful of purèe in a bowl and add a pinch of salt. Swirl the glaze around the potato purèe.

Serve with one of the extra vanilla pods on the side of the dish, so that you smell the vanilla as you eat.