Boil chow mein noodles, drain, and set aside.
Mix beef with soy sauce, oyster sauce, and cornstarch; marinate 15 minutes.
Heat oil in skillet, stir-fry beef 2–3 mins until browned. Set aside.
Add more oil, then garlic and ginger; stir-fry 30 seconds.
Add bok choy, bell pepper, carrot; stir-fry 3–4 mins until tender-crisp.
Return beef and add noodles; toss everything together and stir-fry 2–3 minutes.
Adjust with salt, pepper, and soy sauce. Top with green onions and serve.
