• 24 crayfish or langoustines
• 2 tablespoons of butter
• 2 French shallots, finely chopped
• salt and freshly ground pepper
• 2 tablespoons of cognac
• 2 cups (16 fl oz/500 ml) dry white wine
• 3 tablespoons of tomato paste(concentrated purée)
• 1 tablespoon plain (all-purpose) flour
• 1 tablespoon tomato paste (concentrated purée)
• bouquet garni, made up of six sprigs of parsley, thyme and a bay leaf tied together with kitchen string
• 6 tablespoons (3 fl oz/90 ml) heavy (doucle) cream or crème fraîche
• 2 egg yolks
• 2 pinches cayenne pepper
• 2 tablespoons chopped fresh tarragon

Melt the butter in a non-stick 11-in (28cm) sauté pan. Add the crayfish or langoustines, cover and cook for no more than five minutes. Add the shallots, season with salt and pepper and cook, stirring all the while, over low heat for 2 minutes. Pour in the cognac and ignite, shaking the pan gently until flames subside. Add the wine, tomato paste and bouquet garni and cook over high heat, stirring for 2 minutes. Remove the crayfish with a slotted spoon and keep warm.

Boil the cooking liquid until syrupy, about 5 minutes. Add half the cream and cook for 2 more minutes. Remove the bouquet garni.

Beat the egg yolks with a fork; beat in the remianing cream. Pour into the sauté pan and remove from heat; stir with a wooden spoon until the sauce is smooth and thickened. Add the crayfish and cayenne and reheat, stirring for 30 seconds.

Turn the crayfish and sauce onto a large platter, sprinkle with chopped tarragon and serve immediately.