Marinate the chicken with rice wine (or dry sherry), soy sauce and salt for 30 minutes. Beat egg white and cornstarch together until blended and add to the chicken & marinade. Stir to blend and coat chicken pieces completely.
In a wok or deep sided frying pan heat enough oil to deep fry the chicken pieces. Fry the chicken for 4-5 minutes or until golden brown. Remove chicken from pan, drain well and set aside.
Remove all but 1 tablespoon of the the oil from the pan. Over medium heat stir fry garlic, ginger (and chili flakes if you are using them) for a moment until fragrant. Quickly add chicken to pan, stir gently to coat; add soy sauce, sugar and salt to taste. Stir to combine. Remove from pan and garnish with toasted sesame seeds and diagonally sliced scallions/green onions if desired. Serve hot, with steamed rice.