We pull up at L'Herbe, perhaps the most typical of the area's dozen or so bayside villages—villages where for the past century oystermen have lived and worked in simple gingerbread cabanes with shutters painted vivid shades of periwinkle, kelp, and lobster red, their clapboard sidings trellised with heavy-blooming vines. L'Herbe is a cultural phenomenon in France, where wooden architecture is rare and such an intimate marriage of work and residential life is even rarer. Fauchier, who was born 50 miles up the coast in the tiny village of Vensac, moved here in 1976, after buying a cabane and oyster beds from a local oysterman's widow. He now runs his business with the help of his nephew, Thierry, and Thierry's wife, Marie-Pierre. As soon as he sees us, the couple's young son, Robin, charges across the sand in rubber boots, shouting, "Uncle, I want to drive!" Fauchier gets the tractor from the garage, hefts Robin next to him, then roars back to the anchored boat to haul the day's oysters up to the processing shed next to his cabane. Nearby, oystermen shout and exchange friendly insults with their neighbors, just a few yards away on either side, as they go back and forth between their cabanes and their boats.

Inside the small shed, equipped with a conveyor-belt sifter that sorts oysters by size and a purging pool filled with continually running filtered seawater from the bay, Marie-Pierre begins to tap apart a clump of wild oysters and scrub them with a wire brush. Nathalie Boydens, another employee, lowers the pouches of oysters straight into the pool, where they will remain for about two days, until all traces of algae and sand are flushed out. (By contrast, wild oysters take about eight days to purge.) The majority of mature Arcachon-raised oysters go to customers in the southwest. Most weekends of the year, Marie-Pierre and Boydens drive to farmers' markets in the Dordogne to sell Fauchier's oysters, which are also distributed in crates marked with his name to Intermarché supermarkets in the region. Anyone wandering by his cabane, however, can stop in and buy the freshest oysters at the best price: about four dollars for a dozen.

Once things are under way in the processing shed, Fauchier turns to me and smiles: "Stay and eat a bite?" Living by the tides, Fauchier leaves the oyster beds when the waters will carry him—which is at a different time each day—and when he gets home, he is hungry. Luckily for him, he is a terrific cook: passionate, spontaneous, and, above all, flexible.

Today, he lights a mound of tinder in the grill behind the shed and throws on some grapevine clippings and coconut-size pinecones. We arrange a dozen or so oysters on the grate. They whiten as they heat up and then slowly gape amid the wispy smoke. Fauchier spoons a bit of white wine into each bottom shell and, like a priest serving communion, hands me one. The oyster tastes of earth and sea. "You can pour in beurre blanc, too," he notes. We also feast on a big batch of wild mussels, which he pulled off the sapling poles while we were on the water, steamed in a fennel-scented court bouillon flecked with bayonne ham.

As we eat, Fauchier tells me more about Arcachon's oyster industry. Earlier, he pointed out neat stacks of terra-cotta roof tiles whitewashed with chalk along the edge of the bay, framing one of the least polluted oyster centers in Europe. These are natural magnets for the microscopic naissain, or fertilized oyster larvae, that floats in the water here, he explains. Oysters are hermaphroditic, generating sperm one year, eggs the next. In the summer, they release their laitance, a milky cloud of spawn, and within 24 hours fertilization occurs. After 20 days, fertilized larvae attach themselves to the tiles and begin to form their adult shells. In a good year, 300 to 500 baby oysters will attach to each tile. The mild, stable temperatures, rich plankton, and gentle tidal exchange between the bay and the open sea pamper them, and they grow strong and well shaped. When they are six to eight months old and each about the size of a fava bean, they are scraped off the tiles like corn from the cob. They are then either transferred to chain-mail pouches or the silt in the bay or shipped to other areas in France or other countries, including Portugal, Ireland, and Morocco, to mature. (The chalk-tile system was developed in the early 19th century by an Arcachon stonecutter named Jean Michelet, who discovered that naissain was not only attracted to chalk-coated tiles but actually thrived on them. This revolutionized the oyster industry. Before then, the only oysters the world knew were the rough-shaped wild ones that cling to rocks and are fiercely difficult to pry off.)

Although all Arcachon-born oysters are members of the species Crassostrea gigas—the hollow-cupped mollusks known in France as creuses—those baby oysters that are relocated to other waters will develop their own flavor, unique to the place where they are raised. Arcachon oysters, for instance, are known for their nutty sweetness; they are also held in such esteem that they are currently in the process of being granted Europe's highest agricultural honor: the Identification Géographique Protégée (IGP), a designation that links a European product with its terroir.