Wipe the meat over with a cloth dipped in hot water. Cut it into small, neat rounds about three-quarters of an inch thick. Heat the butter in a pan, put in the fillets and flour, and fry them until they are lightly browned, turning them over once or twice. Next add the stock, stirring it in well. Put the lid on the pan, and let all simmer very gently for about an hour. Be careful they do not boil or even cook quickly, or they will be tough. When they are cooked, strain in any liquor there is from the oysters, and the oysters cut in half. Let these cook gently for a few minutes without boiling.
Arrange the fillets in a circle on a hot dish (they look best one slightly overlapping the other), put the oysters in the centre, and strain the gravy over.