Cut beef steak lengthwise in half, then crosswise into 1/4-inch thick strips.
Combine vegetables and 3 tablespoons water in large nonstick skillet. Cover and cook over medium-high heat 4 minutes or until crisp-tender. Remove and drain.
Heat same pan over medium-high heat until hot. Add 1/2 of beef and 1/2 of garlic; stir-fry 1 to 2 minutes or until outside surface of beef is no longer pink. Remove. Repeat with remaining beef and garlic.
Return all beef and vegetables to pan. Add stir-fry sauce and red pepper; heat through. Spoon over rice. Sprinkle with peanuts, if desired.