Cut the fish in thin fillets size of two fingers, double them and place in close order in a baking dish. Prepare mashed potatoes with yolk of egg mixed in as for croquettes and place a border of it round the edge of the dish.

Take the bones of the fish and stew them in water with onion, parsley, thyme, pepper and salt, making a fish stew or sauce, strain it off and use it to make an oyster stew, into which throw a few shrimps, crayfish, lobster pieces, scallops, mussels and button mushrooms, all or part as may be available. Pour this matelotte or fish stew over the fillets, add a cup of white wine, dredge fine bread crumbs and put the dish in the oven to bake.

Serve one fillet, the sauce that belongs and some of the potato border in the same plate. The name has reference to the sea-coast customs of Normandy.