To velvet the chicken, in a bowl, add the chicken and sprinkle in the salt first, mixing well so it absorbs into the meat. Add the white pepper and rice wine, then mix again. In a small bowl, combine the cornstarch and water to form a slurry, then add it along with the egg white. Mix until evenly coated. Add the cooking oil last to seal the marinade, then let it marinate for at least 5 minutes while preparing the remaining ingredients.
To make the sauce, in a bowl, whisk together the soy sauce, dark soy sauce, oyster sauce, sugar, sesame oil, and chicken stock. In a separate small bowl, mix the cornstarch and water, then stir it into the sauce. Set aside.
To toast the cashews, in a wok over low heat, add 1 tablespoon of cooking oil and the raw cashews. Stir constantly for about 2 minutes until lightly golden and fragrant. Remove and set aside.
To stir-fry the chicken, in the same wok over high heat, add 1 tablespoon of cooking oil. Add the marinated chicken and spread it out. Let it sear briefly, then stir-fry for about 3 minutes until fully cooked through. Add the ginger and garlic and stir-fry for about 10 seconds until fragrant. Remove the chicken and set aside.
To stir-fry the vegetables, in the wok over high heat, add the remaining 1 tablespoon of cooking oil. Add the onion and red bell peppers and stir-fry for about 30 seconds until slightly softened but still crisp.
To combine and finish, return the chicken to the wok and give the sauce a quick stir before pouring it in. Stir-fry until the sauce thickens and coats everything evenly. Add the toasted cashews and scallions, toss well, and serve immediately while hot.
