Place steak in a shallow dish. Add cilantro, half of the olive oil, the lemon peel and juice, garlic, 1/2 tsp. salt, 1/4 tsp. black pepper, and the red pepper. Turn steak to coat. Cover; chill 30 minutes to 1-1/2 hours.
Meanwhile, prepare Lemon Butter; set aside. In a 12-inch nonstick skillet heat remaining oil over medium heat. Remove steak from marinade; discard marinade. Cook steak 15 minutes or to desired doneness, turning once. Cover; let stand 10 minutes.
Add vegetables to skillet. Cook and stir over medium heat 2 minutes or until crisp-tender. Season with salt and pepper. Serve steak with vegetables and Lemon Butter. Makes 4 servings.
In bowl combine softened butter; minced lemongrass; cilantro; lemon juice; and salt, pepper, and crushed red pepper to taste.