The battle of the bouillabaisse: Young chefs are daring to tinker with the classic dish

A long, narrow crouton of homemade focaccia thickly smeared with rouille and studded with slivers of raw vegetables, a glass carafe of creamy tan fish soup for dunking, and a selection of lightly fried fillets of fish. Absolutely delicious, but absolutely not the traditional dish of stewed fish, broth and roundels of toast.

I mentioned Chez Michel to Turac, by contrast. Michel is the most classic of the Marseille fish restaurants, opened in 1946. The staff still wear white jackets with gold epaulettes and it's gained, lost and regained its Michelin star over the decades without, according to its founder Michel Visciano, ever having changed a single detail. Another of the legendarily acerbic M Visciano's quotes, in response to a complaint that the bouillabaisse didn't contain rascasse, which hadn't been in the morning catch due to a force eight mistral, was "Madame, I am a restaurateur, not a meteorologist". Ludovic Turac smiled. "I must try Chez Michel, but it always looked like an old people's home to me." Cheeky lot, the Marseillais.

Another chef, commenting on another rival classic, the Miramar, highly successful due to its prime pitch on the quayside and its red plush Fifties decor, opined that it was "a place for Japanese tourists".

The Miramar and Chez Michel on one hand and Une Table, au Sud on the other represent two ends of the bouillabaisse spectrum; old-school classic, and innovative. The traditionalists follow the Bible, or the Reboul, as it's known, Jean-Baptiste Reboul's 1897 La Cuisinière Provençale, now in its 28th edition. The fish must consist of half a dozen species from a list including John Dory, whiting, conger eel, sea bass, bream and angler fish, known in Marseille as baudroie, galinette or sea hen, gurnard, little crabs, occasionally langouste, or crayfish.

The basic method consists of cooking the fish rapidly in a pan of water, oil, onion, garlic and tomato flavoured with bay, thyme, fennel and saffron, boiled fast so as to amalgamate the liquids, then serving the bouillon poured over the fish and thick croutons of bread.

In modern Marseille, what Reboul calls the bouillabaisse riche has come to predominate, the simple water-and-oil bouillon replaced by a thick sieved reduction of rockfish and shellfish similar to Provençal fish soup, invariably dosed with a slosh of pastis, while most chefs now make their rouille with half olive, half grapeseed oil, emulsified with crushed garlic, ground red Espelette pepper, breadcrumbs and sometimes a little fish broth.

The soup is served first with croutons and rouille, then the plate of fish, with more soup as required.

But that's for the old people's home. Revolution struck in 2003, instigated by one Lionel Lévy, former proprietor of Une Table, au Sud, now executive chef of the new InterContinental Hotel. A decade ago, Lévy unveiled his startling new creation, the bouillabaisse milkshake, which involves a glass of purée of saffron potatoes, emulsion of egg, oil and mascarpone, fish broth foam and poached John Dory. "I was fed up with Marseille being overlooked gastronomically," he told me, "but the milkshake outraged some people."

Nonetheless, it was soon joined by the bouillabaisse hamburger, courtesy of Sylvain Robert, chef at L'Aromat'.

There are two other tendencies: cheap trad and deconstructed de luxe. Cheap trad is the tourist bouillabaisse offered by touts around the Vieux Port for as little as €18 and ridiculed by serious professionals. Though the dish began as a cheap fisherman's staple, thrown together using the poor remains of the catch, the price of increasingly rare rockfish and the large quantities needed for reduction for the rich broth mean that anything less than about €55 is simply not realistic, or so the argument goes.

It's worth mentioning, however, that some cut-price variations on bouillabaisse shouldn't be disregarded: the marmite du pêcheur façon bouillabaisse at the OM Brasserie is a first-rate dish for about €20.

King of the deconstructed de luxe tendency is Marseille's only Michelin three-star, Le Petit Nice, the luxurious Corniche-front domain of Gérald Passédat, a ruggedly photogenic scion of an old Marseille family. M Passédat charges €170 for ma bouille-abaisse, the Citroën SM of fish suppers, whose three-stage specification, shellfish and shellfish fritters in a broth of algae, other fish and shellfish in saffron bouillon, followed by other fish poached in riche soup, does sound pretty rarefied.

One category of bouillabaisse is even rarer nowadays, perhaps extinct: the homemade fisherman's version. Elizabeth David quotes a wonderful meal of just-caught fish cooked over an open fire on the banks of the Étang de Berre: does such a thing ever happen now? Fishermen are having a hard time in Marseille, as everywhere. A dozen stalls are all that remain on the Vieux Port, the main fish market having long ago moved to a warehouse complex down the coast at Saumaty.

Nonetheless, all the serious chefs still buy directly from small boats whose owners will phone them as soon as a choice catch lands on deck. I tried to prise a recipe out of Ludovic Turac's favourite fisherman Sébastien Izzo, as he laboured at the dockside on his boat, where he'd been since 2am, but he didn't respond with sufficient alacrity.

The church of bouillabaisse does have its heretics, it must be said. Elizabeth David apparently wasn't particularly keen. Jonathan Meades, who moved to Marseille a couple of years ago, told me he hasn't eaten a bouillabaisse since he arrived, preferring supions, the delicious little sautéed cuttlefish that are a cheaper speciality of the city. To be frank, I'm a bit of a bouillabaisse agnostic myself, favouring the creamier tomato-less bourride, but that's a different casserole of baudroie.