You can smell what may well be the best grill restaurant in the world long before you step through the door. It's not the harsh, bitter charcoal burn that you get in the British suburbs on a warm summer's evening, when battalions of weekend barbecue warriors set fire to lumps of prime protein and proudly call it dinner. Instead it is something lighter and sweeter – a ripe smokiness that is both gentle and enticing. Certainly it is the only reason you are ever likely to visit the tiny village of Axpe in the cleft of the Basque hills, 45 minutes' drive from Bilbao. For here, in a solid rather than handsome stone building, is Etxebarri – pronounced Etchebarri – a restaurant that has no Michelin stars, uses a cooking method so basic even cavemen would recognise it, and yet has become a point of pilgrimage for food nerds from around the world. Despite being ignored by the tyre company, it has popped up on the list of the 50 best restaurants in the world. Ferran Adrià of El Bulli eats here regularly. Heston Blumenthal had dinner here with his wife just a few weeks ago, and the Australian celebrity chef Neil Perry comes at least once a year and keeps trying to steal the sous chef.
And all this because of the obsessive, often lonely pursuit by a big-shouldered, lightly paunched middle-aged man of what he regards as the purest kind of cookery possible. Put most simply, Bittor Arguinzoniz – Bittor is Basque for Victor – cooks absolutely everything over burning wood. Even the caviar and the cream.
Perhaps you regard yourself as something of a barbecue king. You know about the need to wait for the flames to die down. You understand the power of indirect heat. Maybe you like to throw a few chips of interesting timber into the white-hot ash to spice things up a bit. Compared to Bittor you are a lightweight, little better than the caveman who first cracked the flints together to get a spark because he found raw mammoth a bit tough on the teeth.
When we arrive, a little while before lunch, Bittor is in the woodshed just out the back of the kitchen, selecting logs, with which he will make his fuel. These, however, are not just any logs. He uses different woods for different ingredients. There are gnarled and twisted hunks of vines that are used for meat, I am told, because they are very aromatic. For tranches of salmon he uses pieces of old trees from the orange groves, and for the delicate business of cooking the caviar, applewood. For much else there's a local kind of oak, the sort that produces the acorns eaten by the famed pigs in this region, which is a slow, solid burner. The various logs are destined for the 800°C oven, where they will burn down for that day's service.
Not that he tells me any of this himself. Bittor, 49, is not a big talker. He says he will answer my questions after lunch, but for now he leaves the tiresome business of conversation to his number two, a half-Australian, half-British chef called Lennox Hastie, who learned his trade at le Gavroche and Raymond Blanc's Le Manoir. Later he worked for Michelin three-star restaurants in France and Spain before coming here three years ago where, instead of a massive brigade in crisp whites, there are just the two of them in the kitchen: Hastie had found the place he wanted to be. "Bittor is what he is," he says. "He's very humble. He's very honest. There's no shit with him. He's the best chef I've ever worked with."
He's also completely untrained. Bittor grew up just a short walk from the village asador, or restaurant, in a house where his mother and grandmother cooked only over wood. Although he trained as an electrician, he failed to find employment, so worked first as a lumberjack and then did his military service. At the end of that he decided that the restaurant, which had fallen on hard times, deserved a new lease of life. And in any case, cooking had always made him happy. He took over Etxebarri – the name means "new house" – almost 20 years ago. Soon he was offering a classic Basque grill menu of meat and fish cooked over charcoal in an outside kitchen.
But Bittor is a restless soul, and he started experimenting. He decided charcoal was too harsh and so, around the turn of the millennium, moved backwards to the original wood and took the kitchen inside. He began fashioning metal implements with which to cook using smoke, soldering and welding the pieces together himself. The cooking range is a marvellous self-built Heath Robinson affair: six different grills with different width grids, all of which can be raised and lowered on a pulley system. There are pans with open-mesh bases to allow the smoke to reach the ingredients, and covered pots with big funnel-like holes in the middle for steaming open clams and mussels with smoke. This restaurant, Hastie tells me, is not about dishes and creations. "It's all about the ingredients. Nothing else." He shows me filtration tanks full of live lobsters and crabs, and turbot still swimming about. There is a basket of slippery eels and another of oysters the size of side plates. Mushrooms and green herbs are brought in by foragers and in the winter there is game shot by local huntsmen. Most of the vegetables come from Bittor's own smallholding up the hill, which is overseen by his 86-year-old father.
In the short pause before lunch I ask Bittor where he is happiest, already knowing the answer. He shrugs and glances at the grill. "Here," he says simply. His right-hand man adds: "I deal with all the crap. I enable him to concentrate on those things that make him happiest." They are open for just seven services a week – six lunches and one dinner – but even so, in the busy times both of them have to work the grill. "I grew up with Aussie BBQ so I had lots of preconceptions of what grilling could be," Hastie says. "This is very different. It's addictive, playing with fire. You don't use thermometers. It's all about intuition."
I head upstairs to the dining room, a vault of a space, simply decorated, with bare brick walls and a beamed ceiling, which is overseen by Bittor's wife Patricia. The menu, such as it is, merely lists ingredients: oysters, turbot, beef, pork and so on. Locals do come here just for a hunk of something perfectly grilled, but for gastro-tourists like me they will prepare a tasting menu, which costs from €120-200 depending on what's available. The risk, of course, is that a place like this will get hyped less because of the food than because it ticks a whole bunch of food-fetish boxes: is it a long way from where most people happen to be? Tick. Does it scream authenticity? Tick. Is the chef a hardcore mountain boy with callused hands? Big tick. Line all that stuff up, and the food barely needs to matter.
Oh, but it does. It matters a lot. It starts with three slices of their own smoked chorizo on toast, the smokiness less a brutal kick than a gentle part of the seasoning. They bring a cube and a ball of their smoked butter that they have churned by hand, after a method shown to them by one of the last women who knows how to do it in Normandy. It is so aromatic and dense it can be eaten by itself, like a mousse. There is a single fat oyster, cooked with extraordinary precision as if it was merely introduced to the heat of the grill from the other side of the room. There is that flavour of smoke and then there is the flavour of spankingly fresh oyster. We have a tranche of dense eel and then some tiny baby octopus. Glossy black beads of unpasteurised, unsalted caviar have been held over the grill on seaweed. Cooking caviar is, of course, a crime against gastronomy. Nobody insults the mighty sturgeon by eating its eggs hot or even warm, but here it is a revelation, the oils just running, the flavour boosted by the smoke.
Afterwards Bittor will say: "It is not about the flavour of the smoke; it is about the aroma of the wood that made the smoke." I would love to nod sagely and agree, but I cannot claim to distinguish orange wood from oak. I can tell you that, used with such subtlety and precision, the heat and smoke of burning wood is a wonderful thing. The one piece of familiar grilling is a steak, served on the bone. It has a salty, crisp exterior and a warm purple interior, and the sort of lightly rendered fat that would give Gillian McKeith a seizure. At the end there is an incredibly rich ice cream made from smoked cream, which makes me grateful for the berry sauce that comes with it.
Down in the kitchen, I watch Bittor at the grill, raising and lifting the panels, touching the ingredients gently with his fingertips to check for doneness. He is a man at peace. Occasionally he strides across to the oven with a shovel to fetch more of the burning faggots of wood. He tends to a couple of marvellous-looking steaks as if they were his children and then, as the clock nears five, service is done.
We head out to a roof terrace to sit in the late-afternoon shade, and he points out his childhood house to me, up on the hill. "There were a lot of priests in my family," he says. "So it was a strict upbringing. We were put out to work in the fields from the age of six, and eating was always a sombre moment. Meals were almost religious." In adulthood, he says, he chose a different way, cooking the food he likes and allowing himself to experiment. What, I want to know, is the appeal of grilling? "For me it is the most natural form of cooking there is," he says. "And it has the greatest potential to improve the flavour of any ingredient."
Ferran Adrià, of the self-consciously cutting-edge El Bulli, was recently quoted as saying that Bittor probably couldn't have done what he's now doing "if I hadn't done what I did first". It seems a bizarre, appallingly self-aggrandising thing to say, not least for being patently false. El Bulli is about processing ingredients to sometimes magical effect; Etxebarri is about doing as little to ingredients as possible. "Adrià cooks for the future," Bittor says. "I cook for today."
Is he surprised that people travel from across the world to eat at his small restaurant? "Of course, though it's probably people from other parts of the world who understand it better than local people." The truth is that while what he does is, on a point of principle, remarkably simple, it's not traditional. The Basque way is over charcoal, which he will not do, and down the years there have been some locals who have been suspicious of his cooking. "But as the restaurant becomes better known they are coming round."
As to Michelin, he clearly doesn't care. They send him forms to fill in, detailing his set-price menus, which he doesn't have, and other boxes to tick, which remain defiantly unticked. He thinks that's why he doesn't get recognised by them. "I didn't come into this business to be told what to do or how to do it. What's important for me is not ticking boxes, but whether I'm in front of the fire. I cook for myself. I'll continue to do that even though I can't please everyone." Before I leave I ask him if he has any top tips. He smiles and then barks: "Don't use the bloody charcoal. It destroys any subtlety of flavour. Charcoal is the enemy."
We get it, Bittor. The small boy from the God-fearing family on the hill has a different religion now. It's the doctrine of the wood-burning grill. And he's keeping the faith. OFM
Etxebarri, Axpe near Atxondo, Spain; 094 658 30 42, www.asadoretxebarri.com
Jay Rayner stayed at the Astoria 7 Hotel, San Sebastian; www.epoquehotels.com