Save the water in which any large fish has been boiled, add the scraps left from the fish, and simmer the whole until it is reduced to a quart. After straining, add six potatoes, a carrot and a leek, all sliced, some parsley, and a bay leaf. Let it simmer again for half an hour and then add twelve oysters, a tablespoonful of sherry, a pint of hot white stock, and a little pepper and salt. Cook gently for ten minutes more - or until the oysters are done - and serve as hot as possible.