Cut the chicken into pieces no larger than 3 cm square. Prepare marinade by combining egg white, cornstarch, and 1 tablespoon soy sauce in a large bowl. Add chicken pieces and set aside for two hours. In a deep pot, heat the oil until it reaches 350 degrees. Dredge marinated chicken pieces in water chestnut powder to coat. In a basket, or with a slotted spoon, lower several marinated chicken pieces into the fat. Fry about one or two minutes or until the chicken becomes crisp; test for doneness before completing the batch. Continue until all pieces have been fried. Set oil and cooked chicken pieces aside. In a wok, on high heat, reheat two tablespoons of the reserved oil. Add prepared ginger, scallions, garlic, chili peppers, and orange or lemon peel. Stir to prevent burning. Add the fried chicken and stir quickly.Add sugar, soy sauce, vinegar and cornstarch mixed with chicken stock. Remove from the heat and stir sesame oil into the sauce. Spoon the mixture on to a hot platter and serve immediately with steamed rice. Serves 4.