Velvet the Chicken: In a bowl, mix the sliced chicken with water, cornstarch, oil, oyster sauce, and soy sauce. Use your hands to rub the marinade into the meat thoroughly. Let it rest at room temperature for 30 minutes.
Make the Sauce: In a separate small bowl, whisk together the oyster sauce, light soy sauce, dark soy sauce, MSG (if using), sugar, sesame oil, and white pepper. Set aside.
Prep the Noodles: If using sheet-style fresh noodles, slice them into 1-inch-wide strips. If they're sticking, briefly soak in hot or boiling water to loosen. For dried noodles, boil per package directions until just tender, then rinse with cool water, drain, and toss with 1 teaspoon of oil.
Sear the Chicken: Heat 1½ tablespoons of oil in a hot wok until just beginning to smoke. Spread the chicken in a single layer and cook for 1 minute per side until lightly browned and mostly cooked. Remove and set aside.
Start the Stir-Fry: Pour the remaining 1½ tablespoons oil into the wok. Add the ginger, garlic, and white parts of the scallions. Stir-fry for 15 to 20 seconds until aromatic.
Add the Noodles: Spread the noodles evenly into the wok and stir-fry briefly. Pour the Shaoxing wine around the edges of the wok and toss to combine.
Final Assembly: Add in the sauce and the cooked chicken. Stir-fry everything for 2 to 3 minutes until heated through and evenly coated.
Finish and Serve: Add the bean sprouts and green parts of the scallions. Stir-fry for another minute just until wilted. Serve hot.