Tommi'S Tuna Casserole
["1 lb. cooked elbow macaroni", "1 (8 oz.) container sour cream", "1 medium onion, chopped", "1 can cream of mushroom soup", "1 can tuna fish", "1 stick margarine, melted", "bread crumbs"]
["Saute chopped onion in small amount of margarine until cooked. Mix together cooked macaroni, sour cream, sauteed onion, cream of mushroom soup and tuna fish.", "Spoon into greased baking dish. Bake at 350\u00b0 for 45 minutes.", "Mix melted margarine with enough bread crumbs to make topping.", "Place topping over macaroni and serve."]
["macaroni", "sour cream", "onion", "cream of mushroom soup", "tuna fish", "margarine", "bread crumbs"]