To prepare the chicken: Slice the chicken breasts against the grain into thin, ¼-inch pieces. In a mixing bowl, add the chicken and salt. Toss briefly, then add the white pepper, rice wine, soy sauce, cornstarch, and cooking oil. Mix well and marinate for at least 5 minutes.
To make the sauce: In a bowl, combine the soy sauce, dark soy sauce, oyster sauce, and chicken stock. Mix the cornstarch with water to make a slurry, then stir it into the sauce. Set aside.
To stir-fry the chicken: In a wok over high heat, add 2 tablespoons of cooking oil. Add the marinated chicken and let it sear undisturbed for about 30 seconds. Then stir-fry until cooked through, about 3 minutes total. Remove from the wok and set aside.
To stir-fry the vegetables: Add the remaining 1 tablespoon of cooking oil to the wok. Add the green beans and stir-fry for about 4 minutes, until cooked through but still slightly crisp. Add the onion, garlic, and ginger, and stir-fry for about 30 seconds until fragrant.
To combine everything: Return the chicken to the wok. Stir the sauce again, then pour it in. Stir-fry for about 1 minute, until the sauce thickens and coats everything. Make sure the chicken reaches 165°F (74°C). Serve immediately with steamed rice.