1/2 c. chopped onion
2 tbsp. fat
1 lb. ground beef
2 tbsp. catsup
6 tbsp. prepared mustard
1/2 tsp. salt
1/4 tsp. pepper
1 c. sour cream
8 hamburger buns

Brown onion in hot fat; add and brown meat, mix in remaining ingredients except buns. Simmer 5-10 minutes. Serve hot on toasted split bun. 8 servings.