1. Toss steak in cornstarch until well coated; let stand 10 minutes. Fry noodles according to package directions; set aside.
2. Heat wok over high heat until a few drops of water evaporate immediately. Swirl 1 tablespoon oil in pan to coat. (If using a nonstick skillet, heat oil over medium-high heat.) Add garlic and ginger; cook 30 seconds or until fragrant. Stir in soy sauce, brown sugar, and red pepper. Bring to a boil; cook 4 minutes or until sauce thickens slightly. Transfer mixture to a bowl; wipe wok clean.
3. Heat 1 tablespoon oil in wok over high heat (medium-high, if using a nonstick skillet). Add white onion, and stir-fry 2 to 3 minutes or until tender. Transfer to a bowl.
4. Heat 1 tablespoon oil in wok over high heat (medium-high, if using a nonstick skillet). Add half of reserved beef, and stir-fry 3 to 5 minutes or until meat is browned and edges are crispy. Remove from pan, and repeat with remaining 1 tablespoon oil and remaining beef. Stir in cooked onion, reserved sauce, and green onions. Cook 1 minute or until thoroughly heated. Serve over fried noodles with chili-garlic sauce.