1 lb. lean ground beef
1 med. onion, chopped
1 stalk celery, chopped
1 (8 oz.) can tomato sauce
1 tsp. prepared mustard
1 tsp. chili powder
4 hamburger buns, split
1/2 c. shredded Colby cheese

Combine beef, onions and celery in 1 1/2 quart microproof casserole. Cover with casserole lid and cook on High, 5 to 7 minutes, stirring once to break up beef. Pour off fat. Stir in tomato sauce, mustard and chili powder. Spoon over bottom halves of buns. Sprinkle with cheese and cover with top halves of buns. Serves 4.