Cumberland Sauce
["1 (12 oz.) jar currant jelly", "1 egg yolk", "2 Tbsp. sugar", "1/4 c. raisins", "3/4 tsp. dry mustard", "2 Tbsp. vinegar", "salt and pepper"]
["Melt the jelly in the top of a double boiler.", "Beat in all the other ingredients except the raisins and stir until the sauce is thickened.", "Do not despair if this is slow work; it may take as much as 15 minutes.", "I find I can read a book while I am stirring. When the sauce has thickened, stir in the raisins."]
["currant jelly", "egg yolk", "sugar", "raisins", "dry mustard", "vinegar", "salt"]