1 med. onion sauteed in butter or oil
1 lb. hamburger, brown
1 bottle mild taco sauce (12 oz.)
1 tbsp. vinegar
1 1/2 tbsp. Worcestershire sauce
1 tbsp. mustard (Frenches)
1 1/2 tbsp. sugar

Mix all ingredients and simmer for 1 hour, stirring occasionally. Serve on hamburger rolls.