Michelin-star chef Christophe Hardiquest is Brussels's internationally minded culinary star, but he was raised on the plain provincial specialties of his native Liège.

"When I was a child, I had all the simple things," says Mr. Hardiquest, 35 years old, referring to Liège staples like French fries, meatballs topped with a syrupy sauce, and salade liégeoise, a warm ensemble of green beans, potatoes and bacon.

Christophe Hardiquest Christophe Hardiquest

"My grandmother made good food at home, and that's how I found my way into cooking."

The journey from his grandmother's kitchen to Bon-Bon, his acclaimed Brussels restaurant, took little more than a decade.

Housed in a cramped corner storefront in Uccle, an urbane upscale neighborhood, Bon-Bon has been one of food-loving Brussels's hottest venues since it opened in 2001. Awarded a Michelin star a few years later, the restaurant is often fully booked for dinner several months in advance. The Gault-Millaut Benelux guide, which covers one of the world's denser agglomerations of fine restaurants, named Mr. Hardiquest its 2011 chef of the year.

Now Mr. Hardiquest is taking aim at the constituent parts of his success by making a bold move across town.

The new Bon-Bon, scheduled to open Monday, is in Woluwe-Saint-Pierre, Brussels's grand diplomatic quarter, on the park-lined Avenue de Tervueren. With triple the kitchen space, and nearly a third as many tables, the new restaurant will see its trademark clutter transformed. And the expansive kitchen promises to change the menu, with the chef planning to use his extra space to try out a range of new techniques.

Mr. Hardiquest's inspiration is the whole of Francophone Europe, from the green mountainous Basque country up to flat sandy Belgium, then back down to Provence and the French Riviera. It would be hard to bring its diverse climates and tastes together in a single restaurant, but Mr. Hardiquest has managed to do just that at Bon-Bon. In fact, he has managed to do it in a single dish—an expressionist waffle, flavored with dabs of olive puree and a heady dose of wild thyme, which at once summons up three frontiers of flavor.

Served as a savory appetizer at Bon-Bon late this winter, Mr. Hardiquest's take on the waffle—in its sweet variety, closely associated with his hometown Liege—is another example of the chef's signature approach to food, which combines Spanish and Flemish inventiveness with traditional French reverence for the best ingredients.

In addition to the cooking, Bon-Bon has managed to win a following because of its cozy, club-like atmosphere.

"I am in love with this place," says Mr. Hardiquest, speaking a matter of weeks before the move, while 10 full tables of diners at his Uccle restaurant finish up their long lunches. "But it became too small."

Dominated by wooden floors, dark red walls, and an open, bar-like kitchen, the Uccle space feels more like an Edwardian tavern than a 21st-century Michelin-starred restaurant. It turns out that much of the kitchen is inconveniently hidden behind the dining room, and even extends down into the basement. The new 150-square-meter kitchen will be wide open, says Mr. Hardiquest, "like a theater."

In creating the new kitchen, which uses bright colors to emphasize its openness, Mr. Hardiquest worked with a local architect named Michele Verhelst, whom he chose after viewing her domestic commissions.

"Every project is a challenge," says Ms. Verhlest, who is 32 years old, and a Brussels native. "For this one, the challenge was to put myself in the shoes of a chef." She says that she has used a range of colored glass on the dining room walls, which suggests a "modern translation of lacquer." As Mr. Hardiquest had hoped, "the kitchen is visible from every point of the dining room."

Mr. Hardiquest says that he will stock the kitchen's extra space with new equipment, like his own alcohol distiller, which he can use to conjure up homemade food essences.

Mr. Hardiquest is married to a woman from Liège, and until recently the couple lived with their three young daughters in Uccle, near the original Bon-Bon. Now they have moved to Woluwe-Saint-Pierre, where they are settling into a living space connected to the new restaurant.

Inspired by molecular gastronomy, Mr. Hardiquest often features familiar ingredients utterly transformed by new ways of preparation. One of his most recent creations is a sea bass cooked in a delicate crust surprisingly made out of oysters. And a few years ago, in response to his children's love of pottery, he discovered the gastronomic possibilities of wet clay, or cooking "en tuile," as he calls it.

A centuries-old technique, often used to braise meat slowly, the process involves placing wet clay over ingredients—in effect, firing the pot while cooking the food.

Mr. Hardiquest uses the method to quickly cook a whole duck foie gras at temperatures as high as 200 degrees centigrade. The result is a light, airy, almost mousse-like texture, instead of the heavy, gamey quality that frying usually brings out. In spite of the heat, he explains, "the humidity" inside in the clay "goes away very slowly," while the shell of baking clay keeps the actual cooking temperature inside surprisingly low.

Although he is up on the latest gadgets and methods, he often invokes his Walloon grandmother. Those years in Liège "marked my memory, and that's why my flavors come from the past. I think there is no future in food without the past."

The wonderful bacony undertow of salade liegeoise appeared in an unlikely langoustine course at a recent lunch at Bon-Bon. The shellfish was served with a piece of bacon that had been slowly cooked at low heat for many hours, until it became a kind of bacon custard.

Although Mr. Hardiquest looks to the outer reaches of the Francophone world for inspiration, he is also conscious of helping to forge a pan-Belgian cuisine at home.

"At the moment, it's a bit hard," he says, when asked about the state of Belgian—as opposed to Flemish or Walloon—cooking."

"We have two parts," he says. "Flemish people from Belgium are more open than the French. In Flanders, there is an identity that is technical," which includes a greater interest in molecular cuisine. "The French have more of a 'product cuisine'—good products, good cooks, and nice presentation."

What he wants to find, he says, "is a Belgian identity that is a mix between both."

Mr. Hardiquest is critical of many of France's own great restaurants, which often keep the same menu for years at a time. "For me that's not modern cuisine," he says. "Modern cuisine means improvisation every day."

Bon-Bon doesn't exactly have a menu—you can choose between three, five, or seven courses, and those courses may change from day to day. This means diners who were thrilled this March by Mr. Hardiquest's waffle, or that bacony langoustine, are unlikely to find those dishes the next time they visit the restaurant.

Isn't he bound to disappoint diners? Yes, he concedes, "but I don't care."