Hamburger Barbecue Filling
["12 hamburger rolls", "1 lb. hamburger", "1/2 c. ketchup", "2 Tbsp. vinegar", "2 Tbsp. granulated sugar", "1 Tbsp. mustard", "1 Tbsp. Worcestershire sauce", "1/2 c. chopped onions", "salt and pepper to taste"]
["Get out Mother's heaviest frying pan and put all ingredients, except rolls, in it.", "Cook over medium heat for about 20 minutes, stirring frequently.", "Fill the rolls with mixture.", "Serve hot."]
["hamburger", "hamburger", "ketchup", "vinegar", "sugar", "mustard", "Worcestershire sauce", "onions", "salt"]