Hong Kong-Style Chicken Chow Mein
1 (8 ounce) package Chinese egg noodles 1 cup fresh bean sprouts, or to taste 1 egg white, beaten 1 tablespoon cornstarch 1 tablespoon rice wine (sake) 1 teaspoon sesame oil 1 ½ tablespoons light soy sauce 14 ounces skinless, boneless chicken breast, … 2 tablespoons oyster sauce 2 tablespoons vegetable oil, or as needed 2 teaspoons cornstarch 2 teaspoons water 3 spring onions, chopped, or to taste ½ cup chicken broth ½ teaspoon ground black pepper ½ teaspoon ground white pepper