Sloppy Joes

1 pound ground beef
1 small onion, chopped
½ cup chopped celery
½ cup chopped green pepper
1 (8 oz) can tomato sauce
½ cup catsup
1 T vinegar
1 T Worcestershire sauce
1 tsp dry mustard
1/8 tsp pepper
Hamburger buns

    Combine ground beef, onion, celery and green pepper in a large skillet;  cook until meat is browned.  Drain off pan drippings.  Add tomato sauce, catsup, vinegar, Worcestershire sauce, mustard, and pepper; and bring to a boil.  Cover sauce, reduce heat, and simmer 15 to 20 minutes, stirring occasionally.