Cook the chow mein noodles according to package instructions. Drain and set aside.
In a large skillet or wok, heat the vegetable oil over medium-high heat.
Add the minced garlic and sliced onion, sautéing for about 2 minutes until fragrant.
Stir in the shredded cabbage and julienned carrots, cooking for another 3-4 minutes until the vegetables are tender.
Add the bean sprouts and chopped green onions, cooking for an additional 2 minutes.
Add the cooked chow mein noodles to the skillet, tossing to combine with the vegetables.
Pour in the soy sauce, oyster sauce, and sesame oil, stirring well to coat the noodles evenly. Season with salt and pepper to taste.
Cook for another 2-3 minutes, allowing the flavors to meld together.
Serve hot, garnished with extra green onions if desired.