Cut bacon into 1-inch pieces, and cook in medium saucepan over medium-high heat for 3 to 4 minutes or until almost cooked. Add onion, and cook for an additional 3 to 5 minutes or until bacon is crisp and onion is tender, stirring constantly.
Combine ketchup, apple juice, vinegar, mustard, Worcestershire sauce, pepper, and add to bacon mixture. Reduce heat, cover and simmer until flavors are blended, 15 to 20 minutes.
Stir in sweetener and sliced beef. Serve warm on rolls, if desired.