Cook the chow mein noodles according to the package instructions. Drain and set aside.
In a large pan or wok, heat the vegetable oil over medium-high heat.
Add the minced garlic and sliced onion to the pan. Stir-fry for 1-2 minutes until fragrant.
Add the chicken strips to the pan and cook until they are no longer pink.
Add the carrots, bell peppers, and cabbage to the pan. Stir-fry for 3-4 minutes until the vegetables are tender-crisp.
In a small bowl, whisk together the soy sauce, oyster sauce, sesame oil, sugar, and black pepper.
Add the cooked chow mein noodles to the pan, then pour the sauce over the noodles, chicken, and vegetables.
Toss everything together until well combined and heated through.
Serve the chicken chow mein hot and enjoy!