2 lb. ground hamburger
12 sliced hamburger buns, buttered
2 (10 1/2 oz.) cans tomato soup
2 tbsp. prepared mustard
1/2 tsp. salt

Wrap buns in aluminum foil and heat in a 325°F oven for 15 minutes. Brown beef in skillet. Stir in soup, mustard and salt. Simmer over low heat 10 minutes, stirring occasionally. Spoon into warm buns.