Mix ground beef, bread crumbs, egg, and salt in a bowl.

Shape the mixture into small meatballs (approximately 1 inch in diameter).

Roll the meatballs in a little flour.

Heat butter or margarine in a pan over medium heat.

Fry the meatballs in the pan until browned on all sides.

Alternatively, broil the meatballs in a shallow pan until cooked through.

In a separate saucepan, combine Campbell's tomato soup, brown sugar, Worcestershire sauce, mustard, and vinegar.

Simmer the sauce over low heat for 15 minutes, stirring occasionally.

Add the browned meatballs to the sauce.

Simmer for an additional 15 minutes, stirring occasionally, to allow the meatballs to absorb the sauce.

Serve hot as an appetizer or snack.