It goes off in your mouth like a firework; a kamuro of mango and cheese and Space Dust. I sip my wine and blink. It is perhaps the single most delicious thing I have ever tasted, and it is gone in a second. There has been a lot of food over the last three days. There have been pastries and prawns and Pernod, bars and bouchons and beaujolais, but none of it can compare to this single mouthful. We are sitting in Arzak, a Basque restaurant that lays claim not only to three Michelin stars but also the title of 10th best restaurant in the world, eating the final meal in a culinary journey that has taken us from Paris down through Lyon to end up here, in San Sebastián.
In truth, the gourmandising began on the Eurostar from London, our carriage served with a spread that included mozzarella salad and honey and lavender cake. By the time we got to Paris I was so extraordinarily full that I felt unsure I was cut out for the challenge that lay before me. "I can't imagine ever being hungry again," I told my companion as he devoured a plate of saucisson in the late-night Parisian bar we found. "You will," he said, with meaty certainty. And indeed come the morning, such is the power of patisserie, I could be found in the Gare de Lyon happily truffling for pain au chocolat and strong black coffee.
We arrive in Lyon fortuitously just in time for lunch. This is a city famed for its bouchons, restaurants specialising in traditional Lyonnaise cuisine: rich and hearty, reliant upon sausage and duck and pork. There are around 20 officially certified bouchons in the city, but several other restaurants also employ the term. Our choice is Au Petit Bouchon Chez Georges on Rue du Garet. It is a huddly place with room for just 24, its pink table linen printed with a pattern of white grapes, its windows hung with lace curtains. I do not eat any meat except fish, and as I survey the menu, armed with my somewhat rickety French, I realise that the only thing I can eat is a starter of herring salad. Still, our host and the chef are most accommodating and concoct for me a special salad with sweetly dressed vegetables, radishes and egg. Our carafe of beaujolais is delivered with a good-natured "It's made from grapes. Can vegetarians eat grapes?" The lunch is an exercise in consummate simplicity, my starter, essentially a bowl of herring and potatoes, is rather wan to look at, but tastes astounding. Likewise, I am assured, my companion's salad with lardons and poached egg and his gratin of andouillettes (Lyonnaise sausage).
We are the last people in the restaurant, and the puddings are set out by the till, a seductive sprawl of tarte tatin and stewed prunes. But knowing that we must somehow devour another meal in just a few hours' time we head out into the afternoon, and hire a couple of bikes, wheeling about the city in an attempt to work up an appetite for the evening. It is the most stunning of days: pale and crisp and fresh, the river the colour of duck eggs. As the sun begins to sink, we stop for a bottle of beer by the river, and then pop into one of the little bars that sits aboard the boats on its banks.
Tonight we dine at Le Sud, a restaurant owned by Paul Bocuse, one of the most celebrated chefs of the last century, his name for ever entwined with nouvelle cuisine. Le Sud is one of Bocuse's four brasseries here in Lyon, and the other three are correspondingly named Le Nord, L'Est and L'Ouest, with each establishment specialising in the cuisine characteristic of that region of France.
Le Sud offers a taste of Provence and north Africa, a platter of salmon, aubergine caviar, prawns and rice and chicken tagine, fruit sorbets and chestnut pudding. It is pleasant enough, but neither the food nor the service nor the price can compete with the perfection of our lunch at Chez Georges, and it seems to serve as something of a cautionary tale: chain restaurants, even those curated by a chef of Bocuse's stature, remain largely soulless .
A little chastened, a little fuzzy with red wine, we hotfoot it to the station, and hop aboard our night train to San Sebastián. There are private compartments with cosy wooden bunks, and when we awake it is to morning creeping under the blind and the soft green fields blurring by. My stomach clamours for breakfast.
San Sebastián sits just over the border into Spain, the capital of the Gipúzkoa province in the Basque region (where it is known as Donostia). It is a strikingly pretty city, full of cobbled streets and tiny bars and a promenade that looks over a bay. Though it is February, the weather is warm and joggers shuttle across the sand. The region is home to eight Michelin-starred restaurants, of which one is Arzak. Today Juan Mari Arzak is taking me on a tour of San Sebastián's market.
As we wander through the streets he seems to stop and chatter with every second person we pass - he is, after all, a lifelong resident and something of a celebrity here, but he also diplays the inquisitive nature of a toddler, asking questions, tasting this, touching that; he lifts a small green apple from a greengrocer's shopfront and says with fierce conviction: "This is the most important apple here in the Basque; a little bit acidic, but perfect for cider."
We drift into the fishmarket, a vibrant, bustling collection of stalls that reflects the fact that the people here do not eat a great deal of meat, but plenty of the fish caught in the bay. There are anchovies and langoustines and lobsters roaming their tanks. He shows me trays of percebes (barnacles) and angulas, "the baby of the long snake of the sea", that are incredibly expensive this year, €1,000 per kilo, owing to low production and high demand from Japan. One fishmonger holds up a hake and shows how they cut out the gills, so they may be cooked in a "pil-pil" sauce in a dish typical of the region, and Arzak directs me to a special stall where the local amateur fishermen bring their catch of arraitxiki, a small, bony fish.
We stop at a small cafe for a glass of clarete - a dark rosé (or light red wine, depending upon how you look at it) - and a small piece of mushroom omelette, and on our way out we run into a gentleman whom Arzak claims to be one of the finest barmen in the world. He is 86 years old, small and neat, with a forehead that is smooth and brown. He tells me about his favourite drink, reels off a list of dizzying ingredients: martini rosso, Angostura bitters, curaçao and lemon juice. "Or beer!" he calls as he ambles off into the market.
Outside, the street is lined with produce from the cottage vegetable gardens, all stacked with neat piles of beans and radishes and rich red tomatoes. These are difficult times for local growers; though the supermarkets have yet to dominate the Spanish culture the way they do in Britain, fewer and fewer families are shopping locally and cooking from scratch.
This corner of Spain is famous for "pinchos", small snacks served like tapas. They look quite extraordinary, like a combination of sushi and elaborate patisserie, often small pieces of bread stacked with prawns and egg and whirls of mayonnaise or tiny cones of smooth fish mousse, that cost from around €1.80 to €3.30 for the more intricate creations.
Arzak leads us to Aloña Berri, one of the finest pincho purveyors in town, to sample avocado and langoustine parcels and pig cheek with apricot marmalade, pistachio and dried apricot. "You would have pinchos before lunch or dinner," Rico explains. "In the evenings you would have a couple with a drink, and some people, mostly men, go on a pincho-crawl (a 'txikiteo') and have six or so."
Back at Arzak, the restaurant is preparing for lunch. On the balcony, someone is snipping herbs from the window boxes, and behind the bar the sommelier is pouring us glasses of txomin etxaniz, a local white wine generally served as an aperitif.
We sit a while with Arzak and his daughter, Elena, who is his fellow chef in the restaurant and who is off to Madrid this afternoon to cook for the king of Spain. Arzak grew up in this building, his bedroom above the kitchen, his childhood spent among the chefs of the family restaurant.
He unravels for us the story of his training, the fundaments of Basque cuisine (white sauce, red sauce, salsa verde, salsa negra), his development of a new style of Spanish cookery influenced by the nouvelle cuisine of Paul Bocuse and Raymond Blanc and christened "la nueva cocina vasca". He tells of the day he learned he had won his third Michelin star, how he was at that moment in the kitchen of Ferran Adrià from El Bulli, dining with Heston Blumenthal, and how they stayed up drinking until 7am. And all the while, we are served small morsels of food - the mango and cheese, some of the horrendously expensive angulas in pil-pil sauce, and a hake-based dish, which Arzak refers to as "the most important dish I have made in my life". It is a sort of fish pudding, whose softness honours the cuisine of the Gipúzkoa province; in the other Basque provinces the food is characteristically stronger, but here the flavour and texture are subtle.
We move to the chef's table, inside the kitchen, for what I can only describe as the best meal I have ever eaten in my entire life - a procession of dishes including a tiny wheel of the small bony fish we saw in the market, a white bean and apple purée, the local apple in season, roasted and confited, with olive oil and foie gras, and scattered with fruits, treated with liquid nitrogen so they remain crisp but burst in the mouth. There is lobster with powdered white olive oil that melts when it comes into contact with the sauce - a mix of onion and martini and a saffron-like spice. A salad of greens and tapioca balls is mixed at the table lest the citrus dressing causes the leaves to wilt. White clay and clams are followed by grilled game, red fruit, red wine mousse and a dish named "from the egg to the chicken", which is grilled chicken breast, egg yolk, agar agar and truffle. Monkfish appears, brushed with a mixture of poached onion, ginger and anise, and served with a parsley and ginger sauce, and in a broth with onion and amaranth seed.
Next we move on to roast pineapple with coconut milk, together with something that looks like volcanic stone floating in water, but tastes of chocolate and champagne, and, lest we flag, smoked lemon ice cream, chocolate mousse with spinach and pepper, apricot with kirsch and mango crystals. We drink marquez de riscal, a 1958 Rioja from the Basque, and a muscadet from one of the finest cellars of the region. It is sublime.
They say it is better to travel than to arrive, but I think to myself as I polish off the mango crystals and the madeira, I may have just arrived.
• Laura travelled with Rail Europe, 0844 848 4070, raileurope.co.uk
Five other food tours
Modern Morocco
While you're still never more than a few paces from tagine and cous cous (Al Fassia's is rated as among the best; 55 Boulevard Zerktuoni; 00 212 24 43 40 60) or spicy merguez (at Chez Bejgueni), Marrakech is an unexpectedly rewarding destination for contemporary eating and drinking, too - from Alain Ducasse's deluxe French at Crystal (pachamarrakech.com) to the modern-European-with-a-Moroccan-inflection menu at Kanoun (kasbahtamadot.virgin.com), an hour's drive into the Atlas mountains.
Island hop in Croatia
Croatia's beautiful coastline is lure enough in itself. But the fact that clued-up Italians now make food pilgrimages across the Adriatic for a taste of Dalmatian cuisine, a three-way split between Balkan, Mediterranean and central European influences, seals the deal. Island-and restaurant-hop your way from the roast lamb at Tri Maruna on Krk down to local oysters and risotto at Kapetanova Kúca on Peljesac, mooring up en route at Brac, Hvar, Vis and Korcula for more feasting or to get better acquainted with the country's highly drinkable wines. sailcroatia.net
Chocolate in Turin
If a city can invent not only the choc-ice (known locally as 'il pinguino'), but grissini, hazelnut chocolate (gianduia) and vermouth, too, it's doing something right. Turin, one of Italy's under-the-radar culinary hotspots, is that place. Squander hours over espressos in classic cafes such as Al Bicerin (bicerin.it), pay your respects at high-end chocolatiers Guido Gobino (00 39 011 247 6245) and Peyrano Pfatisch (00 39 011 538 765), then do happy hour Turin-style with a glass of the local moscato d'Asti and a graze of the stuzzichini buffet (the Turinese answer to tapas) at Tre Galli
(3galli.com).
Seafood in Skåne
Kick off your gastro tour of Sweden's south-western province with fish fresh off the boat at harbourside deli/restaurant Fiskrögeri in Skanör (rogeriet.se) before heading to Malmö for TorsoTwisted's multi-course modern Swedish menu, each dish coming with a different wine (torsotwisted.com). And if you're in town for late August, drop by the city's huge, annual, open-air crayfish party. culinaryskane.com
Beer-tasting in Brussels
Gueuze, lambic, kriek, Trappist ale, abbey beer, blonde ale - so intriguingly varied is the Belgium brewing scene that it can turn even a confirmed beer-sceptic into a believer. In the capital, begin your conversion in one of the many old-school bars (aka, estaminets) such as A La Mort Subite (alamortsubite.be) or A La Bécasse (00 32 25 14 44 34).
