Four tablespoonfuls butter, 1 cupful hot water, 1 tablespoonful flour, ¼ teaspoonful salt, ¼ teaspoonful cayenne pepper, 3 tablespoonfuls mustard. Melt half the butter in a saucepan and add the flour, mix and slowly add hot water stirring constantly. When the mixture has thickened add the remainder of the butter, salt, mustard and cayenne. Serve hot with any sliced meat.