In the end securing a table at the best restaurant in the world was pretty straightforward. All I had to do was decide at the age of 15 to become a journalist, then pursue that career with single-minded determination for the next 17 years, until some one had the ludicrous notion of appointing me restaurant critic, cling to the job with limpet-like commitment for the best part of a decade so that I was still in post when, praise be, chef of said restaurant was about to publish a book and was keen to talk to a newspaper about it. Though even then the table wasn't guaranteed. They weren't going to allow me to sit down to eat until I argued that the piece would make no sense unless I had experienced the intense theatricals and dramatics, the mouth fireworks and tongue gymnastics, the long-lauded wizardry and madness and flavour games for which elBulli was famous, all for myself.

Even allowing for that last-minute bout of international negotiations – Ban Ki-moon would have been proud – my method of getting to eat at Ferran Adrià's restaurant in northern Spain really does make more sense than the alternative. There are just 52 seats at elBulli and it is open for only six months of the year, from spring until autumn. In short there are just 8,000 seats available in any 12-month period. These days, for those 8,000 seats, they receive two million requests, a dam burst of desperate, pleading, hungry, saliva-flecked emails fired off at the start of the season, upon which Adrià's staff must stand in judgment.

The interest in elBulli and Adrià may seem at times cultish, verging on the messianic, but in the feverish world of high-end gastronomy, where the pursuit of the next transcendent mouth experience is an end in itself, it does make a warped kind of sense. Since the late 1980s, when Adrià and his team first started pushing the boundaries of food and cooking at their isolated restaurant in the mountains a two-hour drive north of Barcelona, they have never stood still. First they became famous for replacing sauces with foams and for presenting flavours through the medium of warm jellies. As those ideas spread about the world, becoming clichés, they moved on, 'cooking' ingredients in liquid nitrogen or deconstructing famous dishes so that all you could do as you ate them was laugh. Others would be left behind scrabbling to catch up, while Adrià forged ahead. As he would eventually say to me, 'The Bulli is always changing. The Bulli of today is not the Bulli of yesterday.' Just its name, the Spanish for bulldog, has become synonymous with revolution, innovation and – if you really do have an overly developed interest in your dinner – the promise of gustatory rapture and bliss.

It's a hell of a lot to live up to. Indeed, the level of interest causes the restaurant problems. For the past three years it has been voted the best in the world, in The World's 50 Best Restaurants list, run by Restaurant magazine. Panels of judges covering different regions of the world are asked to name their top five, which must be made up of establishments in their region and outside it. The only other rule is that they must have eaten in the nominated restaurants within the past 18 months. So how, furious critics asked when elBulli was yet again named the best in the world earlier this year, can it keep coming out on top when it is almost impossible to get a table?

Even as the chair of the British panel I cannot explain it; nominations are kept secret. But I can say this. Having eaten there, when it comes to drawing up my own nominations next year, elBulli will be right at the top. My meal there was quite simply the best of my life – the most intriguing, the most entertaining, the most delicious – which is a staggering achievement for a place hyped beyond all bounds of sense or logic. I went nursing a fear that I would be disappointed. I left all those fears by a ragged Catalan beach.

All of which makes me hugely grateful for the publication of A Day at elBulli, the book which made my visit possible. There have been elBulli books before, of course, but those are less volumes to be read than catalogues to which one might refer. Assuming what you needed to know was exactly what elBulli was doing with porcini flavoured 'caviar' in 2003. Those huge, £100-plus-a-pop titles, like the exhaustive website, are a complete record of every single dish ever created at elBulli: their ingredients, their plating, their context. And there are many, many hundreds of them. They mark the place out less as restaurant and more as a living museum. Which makes Ferran Adrià less chef than curator. Or, perhaps, artist in residence (last year he was invited to create a central work for the Documenta contemporary art exhibition in Germany, a kind of art Olympics held every five years.)

A Day at elBulli: An Insight into the Ideas, Methods and Creativity of Ferran Adria is a very different kind of book. This one genuinely might sit on a coffee table, and you don't have to be a culinary propellerhead to enjoy it. It does what it says on the cover, but in a very elBulli kind of way. Over 20,000 photographs were taken, and more than 1,200 have found their way inside. From sunrise over the hidden cove it sits upon and the surf lapping at the shore, through Adrià's morning routine to the head-bowed, monk-like devotion of the 50 or so cooks and their mis-en-place, the invention of dishes, the drawing-up of menus, the opening of the gates, the dinner service and the clean-down to the final turning of the key in the lock, everything is here. It is detailed and intense. It is knowingly arty. It puts the phwoar into gastro-porn.

The irony is, of course, that the chef is such a celebrated figure, in his native Spain such a national hero, that the routine the title suggests is now a rare luxury. Initially we asked that we be allowed to spend a day with Adrià. I imagined sipping thimbles of hot black coffee with him as the sun rose and then following him through the studious process of providing diners with a once-in-a-lifetime experience. But that wasn't going to happen. Too busy. Too many people to talk to. Too many things to consult upon. Instead we would be allowed just a few hours, and so I drew up a plan: how long we would conduct a formal interview, some time in the kitchen, a conversation about the creation of dishes. What I hadn't bargained with was the chaotic, ebullient, performer that is Adrià himself. I made plans and the moment we met every single one was thrown out the window.

I should have seen it coming. For the past three years, at the end of The World's 50 Best Restaurants event in London, Adrià has been invited to
make a speech, and it has always been a drawn-out affair. His sentences are long and complex, and loop around on each other in a way that leaves poor translators rushing to catch up. His arms rise and fall with every clause and noun, and he is never done until he has invited every other Spanish chef in the room up on to the stage to link arms and sing 'We are the World'. Or something like that. By that point the translator is usually sobbing in the corner. It is not the highlight of the night, but it is very Adrià.

And that's exactly what I get when we meet, on the terrace at elBulli: something rambling and passionate and hard to keep up with. The food served here may be decidedly modernist, looking to the future rather than the past, but the space in which it is served is homely, a hacienda-style lodge of rough-hewn stone and gnarled black beams and whitewashed stone shelves stacked with what look like old family portraits in tarnished frames. Adrià suits the space. There is nothing sleek or, heaven forfend, hip about him. He is a short, stocky man of middle years, with a mop of curly hair which he probably has to be reminded to get cut now and again. He listens intently to me as the translator explains my plan – the set-piece interview, the tour of the kitchens, the exposition – nods at every point, says that's a great idea but then announces, a finger raised. 'But first I must explain to you the Bulli.'

And we are off. We never sit down at all. Instead the interview is conducted entirely on the run. First he insists on describing the history, how it was opened in 1961 as a beach cafe and only slowly developed into a restaurant, the Michelin stars that it won and lost, until he arrived after military service in 1983, becoming its head chef a year later. In those days, he says, elBulli was in thrall to the ways of nouvelle cuisine, the movement which, in its purest form, eschewed the butter and cream of the Escoffier generation in favour of lighter, brighter, sharper flavours. With its love of fiddly curls of avocado and kiwi and its tiny portions it was eventually much mocked and pilloried, I say. He shrugs. 'Those who come up with something new are always criticised.' He describes himself as a student of nouvelle cuisine, says it is what 90 per cent of gastronomic restaurants are practising today.

He picks up a copy of elBulli: 1983 to 1993. It is stuffed with pictures of the food they were serving then, bright colour plates full of scarlets and oranges; dishes of red mullet with tiny cubes of aubergine or fiddly dice of tomato with teeny slivers of meat served rare. There are dishes in there which are exact copies of others by the big gastronomic names of the day like Georges Blanc or Mark Haeberlin, whose food Adrià had studied. Slowly, he says, they decided to attempt a site-specific kind of nouvelle cuisine, something which suited Spain in particular. He shows me a picture of a dish which he says is based on gazpacho, the various elements served dry around the plate rather than as a soup.

Trying to sound clever I ask if that is one of his first deconstructions, the essentials of a dish taken apart and reconfigured so that you might consider it anew. He looks intensely at me, as if I am a promising but lazy student who has let myself down. 'No, no. This is an adaptation. With an adaptation you will always see the differences.' With a deconstruction it is less immediately obvious. Right.

He picks up another volume and shows me a flow chart. It is a timeline of elBulli's food and its developments. Here, in the late 1980s, is where they started working on adaptations. Here, in the early 1990s, the deconstructions come in. Next, the foams and the jellies and so on. This, he says, is what I must understand. 'The mid-90s is when we started to create a new language.'

Most leading chefs I have interviewed talk at some point about the land and nature's bounty. They reference some eye-moistening experience at their mother's apron strings. Not Adrià. The words he uses most are 'discourse' and 'language', 'creativity' and 'innovation'.

'The Bulli is about creativity,' he says, a finger raised. 'If you don't understand this you don't understand the Bulli.' And ' creativity is a very fucked-up issue. It's not a game. It's not about playing around. It's a serious business.' For six months of the year, while the restaurant is closed, Adrià retreats with his brother Albert, the pastry chef, and his key lieutenants, to a workshop in Barcelona – the Taller – to develop the menu for the next season. But these are never ingredient-led affairs. It is never about anything so banal as what they can do that's new with duck or seaweed or chocolate. It's all about method. 'To develop a new language you need a new concept, a technique, an elaboration.'

'Who came up with beating three eggs and making an omelette,' he says, ' that's a new elaboration, a new technique.' The same is true, he
says, with the mixing of flour with water to make pastry, to make dough, which in turn lead to the creation of thousands of new dishes. 'Our dream is to be able to make new kinds of pastry or omelettes which in turn lead to new dishes.' To do this, over the years they have begged, borrowed and stolen. They have adopted Japanese techniques for making warm jellies from seaweed extracts (rather than from animal-based gelatins which melt just above room temperature). They have plundered industrial food processes, of the sort used to make the little jellies of pimento in the middle of stuffed olives, or mass-market emulsifiers of the kind used in salad dressing to make foams stay stiff. Sometimes they have built whole riffs around the art of happy accidents. They freeze-dry things. They vacuum-pack. They use pipettes and distillers. 'The more unique a language you create the fewer people understand it,' he says. 'For many people coming to the Bulli for the first time, it's like being spoken to in Japanese.' But here is what's changed, he says. Some years ago people eating there were simply baffled or dismayed by what they were being served. 'Now the people who come here are willing to be open to the experience.'

And yet, he says, the restaurant is misunderstood. People assume it's all about the science, that it's whizz bang and pointy headed. I suggest he complains too much. After all isn't that his fault for constantly banging on about the need to innovate? He agrees that he is partly to blame, and mentions a photograph of him and Heston Blumenthal of the Bulli-esque Fat Duck – the two are firm friends – surrounded by clouds of vapour from liquid nitrogen. 'The science issue is a monster we must kill.'

What he says we all must understand is that his kitchen is still a kitchen. 'There are 70 people working at elBulli. It is very artisanal.' And he leads me into it. There is no door; the front of house and kitchen flow into each other organically, but where the dining room is classical Spanish, the kitchen is full of clean, sharp lines and flat surfaces. It is a kitchen as imagined by James Bond designer Ken Adam. At the back is an acre of plate-glass window looking out on to the ragged rust-coloured rock of the cliff face. In front of that are three long workbenches. The middle one is surrounded by at least a dozen young cooks, heads bowed over tiny, intricate preparation works. They stand there for hours, are there mid-afternoon and still there all the way through the dinner service. Fewer than a dozen of the kitchen staff are paid to work at elBulli. The rest – like our own Jason Atherton of Maze one year – come here simply for the experience and to work for free.

The bench on the right, he tells me, is where new dishes are being developed. Although a lot of menu development takes place off-season they open each season with the previous year's dishes, slowly but surely replacing them with new ones, those in turn being replaced. In all there are three menus a year. 'A few dishes stay on all year. Others are seasonal or involve rare ingredients so only stay on for a short while.' Next to us is a tiny pan containing a lightly steaming cloudy jelly with what looks like two chickpeas in it. 'When they cook chickpeas in the market the stock at the end turns into a jelly.' I am invited to try one of the chickpeas. It tastes as I expect at first, and then a nuttiness comes in. 'They are fresh hazelnuts,' the young cook next to me says, with a grin. 'This is not a finished dish,' Adrià says. 'It is an idea.'

As we talk another cook hands him a thin, crisp disc of dried fig, with a smear of something flavoured with vanilla and salt. 'We are looking to create a snack,' he tells me. He nibbles, looks off into a distant corner and then issues a command. Try something else with it. Now he's given a little crisp made of dried, toasted rice. 'This is what you get at the bottom of a paella pan when it starts to stick. We are thinking of making something with it.' There is a flat red disc, of concentrated dehydrated tomato, like a communion wafer, and then a tiny aubergine that has somehow been manufactured to look like an olive. Everything here in the low-lit kitchen is tiny, thimble sized, but in the mouth they clatter around with flavour.

'Cooking is about how things taste,' he says. 'Obviously we use technology but that's not what matters. What matters is that you, the eater, finds it magical. It's an experience between the creator and the eater.' I ask him why he has decided to publish this book. 'I did this because I wanted to let people who couldn't get here visualise what it's about.' He admits that he could sell seats in his restaurant on eBay for thousands of Euros a time, that he could have 25 elBullis around the world and make a mint. But he doesn't. Instead there is just this one and, despite charging €200 for the menu per head, excluding drinks, it operates at a loss. It is all the other businesses – the consultancies with hotels, the more casual restaurants, his work with mass-market food producers and, yes, the books – which make the money. So is he now more of a communicator than a cook? He shakes his head. 'No, above all I'm a cook.' But more people consume his food by reading about it than eating it. 'It's the only thing I can't fix. It's a real shame. We're not proud of it.'

It is heading towards six o'clock and I can feel the mood changing in the kitchen. From a sense of quiet industry, the pace has picked up. In the dining room, tablecloths are being ironed, cutlery laid. Adrià says it is time for him to crack on and for me to go. He has issued orders. I am not simply allowed to stay here until dinner. El Bulli sits on a cove a 20-minute drive along a mountain road of hairpin bends from the tourist resort of Roses. Adrià has ordered me to go back down there to my hotel, to freshen up, change and then come back. He has also asked that I do not drive myself back. 'You need time to relax, to swap from interviewer to diner.' I like taking orders from Adrià. I do as I am told.

When it was over, when the last of the 42 (tiny) items we were served had been cleared away and we had drunk our espresso and finished raiding the cigar humidor containing only handmade chocolates and been given our individual menus, what stayed with me was the attention to detail. While for the diners it is a once-in-a-lifetime experience, the staff have to do it every single night. And yet there is nothing jaded or casual about it. They not only accept, but embrace the notion of the singular event. Waiters happily take photographs of diners posing next to the elBulli sign outside. Every guest is led into the kitchen to meet Adrià and to have their photograph taken with him, and he falls into position next to them with ease. Enquiries have been made beforehand over allergies or dislikes so every table can be told, truthfully, that the menu that evening has been tailored to them (though, in truth, there is no choice. Only one tasting menu is served and most people get exactly the same dishes.)

It begins with a hollow sphere of ice, containing meltwater, to be sucked through a hollowed-out vanilla pod. The effect lies not just in the refreshing water with a hint of vanilla, but in the visual: the miraculous ball of ice which forces you to think of mountain air. Next, a cocktail of lemon and grappa and yoghurt, but served as a cream with a sugared surface as a very adult crème brûlée. And alongside this, tiny, dolls'-house tangerine segments, manufactured God knows how, which burst under the slightest tongue pressure. We are brought what looks like an ostrich egg, gently steaming with icy vapour. It is broken at the table. It feels in the mouth like an unsweetened white chocolate but tastes of very mellow coconut, which we are to dust with Indian spices.

After an orchid flower, whose leaves have been made from a brittle paste of passion fruit, we are presented with a children's tea party of snacks: intense discs of parmesan, dark bitter-chocolate pyramids flavoured with pine nut, powerful crisps of tomato. And then, best of all, plump olives laid on a spoon before us.

They are the colour and shape of olives but glisten and shudder. We put them in our mouths. It is the first example this evening of elBulli's current favourite technique – spherification – a liquid, purée or gel set within a tight membrane so that in the mouth it bursts releasing a rush of flavour, in this case the pure essence of olive. It works by dropping a ball of the purée into a setting agent, hence the sphere. They also do this with bright, milky mozzarella. But at elBulli they have worked out how to create shapes with it: tiny triangles of 'pesto' ravioli, say, or a long thin tube flavoured with miso and ponzu to accompany a razor clam. The latter also speaks of another recurring them, which is Japanese flavours and spicings. It is a curiously Asian meal.

It is also full of whimsy. There is candyfloss encasing beautiful fronds of perfumed wild flowers. There is a set of odd-looking mouthfuls on a plate that, eaten together, taste exactly like spaghetti carbonara. We are presented with a single 'oyster leaf' holding a bead of shallot vinegar, and blow me, if the leaf doesn't taste exactly like an oyster. My companion is Stephen Harris, the chef from the Michelin-starred Sportsman pub near Whitstable. He announces he is going to find a supply of oyster leaves the moment he gets home. We have braised tomatoes injected with olive oil. Stephen spears one with a fork and it sprays juice across the table. 'Well,' he says, gleefully, ' if you're going to serve me fabulously weird shit like this, that sort of thing is bound to happen.'

There is a single strawberry braised in gin and gnocchi made from jellified egg yolk, and a deconstructed walnut, endive and Roquefort salad. Most strikingly there is very little meat. There is a single cylinder of intensely savoury veal tendon, long braised unto jelly and filling the mouth with the essence of baby cow, and another plate dressed with tiny shards of suckling pig and alongside it a ham consommé bobbing with cubes of melon. But that is almost it on the animal-protein front. Few of the dishes are complex. They rarely attempt to make an impact through weird unimagined flavour pairings. It's about intensity and delivery.

Does everything work? No, not entirely, and it's the weirdest that fail most. We are served a plate of a very sour Colombian fruit with the texture of mango that is then dressed with a pile of 'tagliatelle' made from frozen foie-gras fat. It has a curious, even unpleasant, cheesy back taste. There is another dish of a coconut cream and jelly which tastes of not very much at all. But those two duds – and there were only two – were more than can-celled out by the highs. Best of all: a crisp wafer of bitter chocolate laid with a game mousse – an oddly established combination these days – the flavour of which just went on and on. Stephen and I stared at each other across the table, our lips closed, and then silently began giggling, at a shared, if wistful joke.

And all of this at a beautifully steady pace, as if a metronome were setting the rhythm of our meal. We were never without something to eat for more than a couple of minutes. We felt looked after, cared for, nurtured. The food we had been served may well have been at the very cutting edge, but the effect it achieved spoke to the eternal verities and virtues of great restaurants. And if that makes it sound like dinner at elBulli had sent me off on one, propelled me towards the pseuds'-corner realms of adolescent poetry and lovesick devotion, well, guilty as charged. What can I tell you? I'd had a good dinner.

I do not get to speak to Adrià again that evening. He is too busy seeing out the performances for the other diners who started later than us, but I keep thinking about something he had said that afternoon. 'I don't cook for other people,' he told me. 'I cook for myself.' It is, he says, all about happiness, his own and that of his diners. 'The happiness is the challenge which pushes us forward. It would be quite sad if we couldn't make people happy.' As our cab navigates the hairpins at frightening speed, I sit back in my seat, a picture of calm, and I conclude that I am very happy indeed. Ferran Adrià's work for the day is done.

· Read more from Jay Rayner on meeting Adrià and let us know what you think on the blog