Heat broiler. Sprinkle black pepper on both sides of steak, pressing into meat.
Broil steak 5 inches from heat for 12 to 15 minutes, turning over halfway through cooking for medium. Let stand 10 minutes.
Meanwhile, heat oil in nonstick skillet over medium heat. Add onion and red pepper; cook 3 minutes, stirring. Increase heat to high. Add mushrooms; cook 6 minutes or until mushrooms release their liquid. Stir in teriyaki sauce, lemon juice and drippings. Bring to simmering. Remove from heat. Slice steak. Serve with sauce. Makes 6 servings.