1 (3-4 oz.) can mushrooms
1/4 c. chopped onion
1/4 c. chopped green pepper
2 tbsp. butter
2 tsp. flour
1/4 tsp. salt
Dash pepper
1/2 c. Heinz tomato ketchup
1 (6 1/2 - 7 oz.) can tuna, drained

Drain mushrooms, reserving liquid. Add enough water to mushroom liquid to measure 1 cup; set aside. Saute the mushrooms, onions and green peppers in butter until they are tender. Stir in flour, salt and pepper into vegetables, then stir in mushroom liquid and ketchup. Heat slowly, stirring occasionally, until sauce is thickened. Add tuna; heat. Serve over hot buttered rice.