Combine cornflour with soy sauce in a small bowl, then stir in oyster sauce, Chinese cooking wine, sugar, sesame oil, and pepper to complete the sauce mixture.
Pour 1 tablespoon of the sauce over the sliced chicken, mix to coat evenly, and allow it to marinate for 10 minutes.
Cook the chow mein noodles as directed on the package, typically by soaking in boiled water for one minute. Drain thoroughly.
Heat the oil in a wok or a large frying pan over high heat. Once shimmering, add the garlic and stir-fry for approximately 10 seconds until it begins to brown.
Introduce the marinated chicken and stir-fry for about 1 minute, just until it starts to brown but remains uncooked inside.
Add the shredded cabbage, julienned carrot, and the white parts of the green onions. Stir-fry for 1½ minutes until the cabbage softens.
Toss in the drained noodles, pour over the prepared sauce along with 1/4 cup of water, and stir-fry for 1 minute, ensuring everything is well coated.
Add the bean sprouts and the green tops of the onions, and toss for another 30 seconds until the sprouts just begin to wilt.
Remove from the heat and serve hot without delay.