Boil noodles according to package instructions and drain well.
Toss sliced chicken with cornstarch and black pepper.
Heat oil in a wok or large pan over high heat.
Add chicken and stir-fry until cooked through.
Add minced garlic and sauté for 30 seconds.
Add bell peppers, cabbage, and carrots and stir-fry for 2–3 minutes.
Add cooked noodles to the pan and toss to combine.
Pour in soy sauce and oyster sauce and mix well.
Drizzle sesame oil and stir-fry for another minute.
Garnish with spring onions and serve hot.