1/2 c. chopped onion
1 tbsp. butter
1/2 c. ketchup
1/4 c. Worcestershire sauce
1 can tomato soup
1/4 c. vinegar
1/4 c. water
2 tbsp. sugar
1-2 lbs. cooked or boiled ham, sliced very thin

Mix all ingredients except ham and cook over low heat for 1 hour. Stir frequently, keep top of pot on. Add ham and stir. Serve on hamburger buns.