Anybody who has eaten Bruno Loubet's famed hare royale dish at his restaurant in London's Clerkenwell will recognise the work of a chef schooled heavily in the French tradition. There are swirls of purees and jus but at its centre is a hunk of animal; one of the most bloody and intensely earthy of animals. It feels very much like the work of a cook born in Bordeaux, the place where they like to top their cote de boeuf with bone marrow, and sear it fast so that inside it is still the colour of raging knife cut. He's a Frenchman. He knows how to do meat.

All of which makes the dish I am now eating all the more intriguing. It is a faux merguez sausage made with chickpeas and cumin and paprika, served alongside a pod of peas grilled to open and a preserved lemon salad. It is a punchy dish which involved nothing with a pulse other than the chef who cooked it. During my meal, it is not an isolated incident. There is a whole cauliflower, pot roasted with caraway seeds and buttermilk until it becomes something soft and rich and luscious. Even where meat or fish appears it is not as the star of the show but, in a neat reversal, more as a garnish. There are some seared peppers padron with salted almonds and only a few flakes of salt cod. On another dish, there is a robust cake of quinoa and corn with a silky red pepper sauce and alongside it, almost as an afterthought, a thumb-sized cube of pork belly.

Bruno Loubet has gone the way of the vegetable. "I just feel we have been eating too much meat," Loubet says simply, when he sits down with me after the lunch service. "It's about health but it's also about flavour." And he means it. These dishes he has just served me are not just some small personal experiment; they are at the heart of the menu of a major new restaurant he will be opening in King's Cross in June. Grain Store, which will seat 140, with more on a terrace and at the bar, is not a vegetarian restaurant, but it is a restaurant where vegetables get more than equal billing.

It's a place where the reference to salmon confit in a dish of a peach and watermelon salad comes last; where you hear about the pickled cucumbers, raw turnips and broad beans before any mention is made of the lamb belly; where many of the dishes – salads, stews, grills – have no meat or fish element at all. It's been tried before, for example at the Field Kitchen in Devon when the great Jane Baxter was at the stove. But bringing something like this to the capital with its cult of steak restaurants, dirty burger joints and barbecue places is a different matter entirely.

"I really don't want to run a vegetarian restaurant," Loubet says. "But there's a massive palate out there. People hear carrot and think grated or boiled but you can do so much more." Plus, he says, it's also more of a challenge. "A piece of meat is an easy escape for a chef," he says. "It's easy to please people with that." It will also allow him to offer serious value. "This won't be about steaming some veg, throwing on a little extra-virgin olive oil and charging 20 quid."

Partly, he says, the project is a throwback to his upbringing. Bordeaux may be associated with hunks of grilling beef with sauce bordelaise, but that was not his experience. He was one of seven kids, in a family of meagre means, who got most of their fruit and vegetables from their own allotment. "When I was a child we couldn't afford meat every day. At the time I felt disadvantaged, but now I feel privileged. One of my jobs was to pump water to the allotment and afterwards I would sit and eat radishes washed straight from the ground, or tomatoes from the vine."

After training at culinary school in Bordeaux, he moved to Belgium then Paris and finally landed a job in London at Pierre Koffmann's La Tante Claire. An illustrious career – at the Four Seasons, as head chef at Raymond Blanc's Le Manoir, in charge of his own restaurants here and, for nine years, in Australia – brought him back to London in 2009 to open Bistrot Bruno Loubet at the Zetter hotel. That will continue alongside the new venture.

So is this just about taste and health? "No. It's also about sustainability. I am trying to make my chefs at the new place understand the whys and whats. I don't want them just to do a job. I want them to know that it takes seven kilos of grain to make a kilo of beef. I want them to know what raising meat does to the environment." In some ways, he says, it is a compromise; that there will always be demand for "a little meat" and that this must be serviced. Even so, he says, big ideas need to start somewhere. "I like to believe that in 10 years it will become the norm for restaurants to cook this way." Bruno Loubet is on a mission. He wants to change the way people look at their food. And he's pursuing it one restaurant at a time.

Grain Store will open on 10 June