Wash the tails, dry well and remove any superfluous fat. Cut into joints and divide the thick parts in half. Melt the fat in a saucepan, fry the pieces of tail until brown, then remove from the pan. Slice the onions and fry them until light brown, add the flour, mix well and fry slowly until a good brown colour. Add the stock or water, salt, pepper, bouquet garni, cloves and mace and bring to boiling-point, stirring all the time. Return the pieces of tail and simmer gently for about 2½–3 hr. Remove the meat and arrange on a hot dish. Add the lemon juice to the sauce, correct the seasoning, strain and pour over the meat. Garnish with croûtons of fried bread and diced or thin strips of cooked carrot and turnip.