Make the Sauce: In a small bowl, combine the soy sauce, oyster sauce, sesame oil, cornstarch, and sugar. Whisk until smooth and set aside.

Cook the Chicken: Heat 1 tablespoon of vegetable oil in a large wok or skillet over medium-high heat. Add the sliced chicken and cook for 4-5 minutes, or until golden brown and fully cooked. Remove the chicken from the skillet and set aside.

Stir-Fry the Vegetables : Add the remaining 1 tablespoon of vegetable oil to the same pan. Stir in the garlic and ginger, cooking for 30 seconds until fragrant. Toss in the onion, carrot, bell pepper, and cabbage. Stir-fry for 3-4 minutes until the vegetables are just tender yet still crisp.

Combine and Cook : Return the cooked chicken to the pan along with the bean sprouts and cooked chow mein noodles. Toss everything together. Pour the prepared sauce over the mixture and stir-fry for 2-3 minutes until everything is well-coated and heated through.

Serve : Remove from heat and serve hot. Top with chopped green onions or a sprinkle of sesame seeds, if preferred.