2 1/2 pounds Ground beef -- lean

1 Onion;large -- quartered

1 cup Ketchup

1 teaspoon Chili Powder

1 teaspoon Dry mustard

1 teaspoon Salt

2 cups Beef broth -- OR water

8 Hamburger rolls -- toasted

In skillet, brown ground beef; drain well. Place browned beef and remaining ingredients except hamburger rolls in crock-pot. Cover and cook on LOW setting for 6 to 12 hours. Taste for seasoning before serving. Serve spooned over toasted hamburger buns. 6 to 8 servings