PREHEAT broiler. Wrap handle of 10-inch nonstick frypan with foil. Cook vegetables and hash browns in 1 Tbsp. oil in frypan over medium heat for 15 min.

MIX eggs with 1/4 cup water and mustard; pour mixture into frypan and cook until almost set.

SPRINKLE with cheese. Broil 5 min. or until cheese is melted.