Preheat broiler. In a large microwave-safe bowl combine vinegar, sugar, and black pepper. Add beef and sweet peppers. Cover and cook on 100 percent power (high) for 4 minutes.
Meanwhile, split rolls and place cut sides up on a baking sheet. Broil 3 to 4 inches from heat for 1 minute or until lightly toasted. Top each roll with cheese; broil 1 to 2 minutes until cheese is melted.
Using a fork, coarsely shred beef. Stir in parsley. With a slotted spoon, mound beef mixture onto rolls. Sprinkle with additional snipped parsley. Serve with any remaining cooking liquid.