BROILED MACKEREL À LA FLEURETTE

Split a Spanish mackerel, remove the bones, and season with salt, pepper, and olive-oil, basting with oil as needed. For the sauce, cook in a saucepan, without browning, four chopped shallots, two tablespoonfuls of vinegar, a teaspoonful each of chopped chives and parsley, salt, pepper, and grated nutmeg to season, two tablespoonfuls of melted butter, and a tablespoonful of flour. Cook until smooth, stirring constantly, take from the fire, add two tablespoonfuls of butter and the juice of half a lemon, pour over the fish, and serve.