Clean chicken pieces well. Dab dry completely with kitchen paper towels and use a meat mallet to lightly tap on the meat side of the chicken to tenderise it.
Combine seasoning ingredients in a mixing bowl. Put the chicken pieces into the seasoning ingredients to mix. Leave aside to marinate for 1-2 hours.
Heat enough oil in a wok until hot. Coat chicken with cornflour. Shake off any excess flour then deep-fry in medium hot oil until the chicken skin turns lightly golden. Remove and leave aside. Turn the heat to medium hot. Return the chicken to the hot oil. Turn and fry until golden brown and crispy. Dish out and drain from oil. Serve immediately, if preferred.