PREHEAT oven to 450˚F or preheat grill to medium-high. Sprinkle both sides of steak with garlic powder and pepper; cut in thin strips. Combine steak strips, mushrooms and teriyaki sauce.
CENTRE ¼ of steak mixture on each sheet of ALCAN® Heavy Duty Aluminum Foil. Top with green onions.
BRING up foil sides. Double fold top and ends to seal packet, leaving room for heat circulation inside. Repeat to make four packets.
BAKE 12-15 minutes on a cookie sheet in oven OR
GRILL 7-9 minutes in covered grill. Serve over noodles.