Marinate the chicken in soy sauce, cornstarch, rice apple vinegar, ginger, garlic, sugar, and white pepper for at least 30 minutes.
Cook the lo mein noodles according to package instructions; drain and toss with sesame oil.
Prepare the lo mein sauce by mixing soy sauce, oyster sauce, sesame oil, brown sugar, cornstarch, chicken broth, vinegar, ginger, garlic powder, and red pepper flakes in a bowl.
Stir-fry marinated chicken until cooked through and set aside.
Stir-fry vegetables until tender-crisp and then add the lo mein sauce. Simmer until thickened.
Return chicken and noodles to the wok; toss well to combine.