Arrange bacon in a single layer in large unheated skillet. Cook over medium heat 12 to 14 minutes or until crispy, turning often. Drain bacon on paper towels; discard drippings in skillet.

Cook ground beef in same skillet over medium-high heat 5 minutes, stirring occasionally to break into crumbles. Add chopped yellow onion; cook 3 to 5 minutes more or until beef is browned (165°) and onion is softened.

Reduce heat to medium-low; add soup mix, yellow mustard, and Worcestershire sauce. Cook 2 to 3 minutes more or until sauce begins to thicken.

To serve, place bun bottoms on 6 serving plates. Top with ground meat mixture, cheese slices, red onion slices, bacon, and bun tops.