Heat grill. Brush both sides of steak with 2 tablespoons of the teriyaki sauce; sprinkle both sides with pepper.
When ready to grill, place steak on gas grill over medium-high heat or on charcoal grill 4 to 6 inches from medium-high coals; cover grill. Cook 10 to 15 minutes or until steak is of desired doneness, turning once.
Meanwhile, spray medium nonstick skillet with nonstick cooking spray. Heat over medium-high heat until hot. Add bell pepper; cook and stir 2 minutes. Add mushrooms with liquid and remaining tablespoon teriyaki sauce. Cook 2 to 3 minutes or until thoroughly heated and bell pepper is tender, stirring occasionally. Serve sauce over steak.