To make the marinade, mix together the soy sauce, shaoxing and sugar with the chicken, and leave to marinate for 20 minutes.
Heat a wok until just smoking. Add half the oil and, when hot, stir-fry the chillies until they blacken. Add the chicken and cook undisturbed for 1 minute, allowing the chicken to start browning, then stir-fry for 1 minute, or until the chicken is brown on all sides but not completely cooked through. Remove.
Heat the remaining oil in the wok and stir-fry the garlic and ginger until fragrant. Add the capsicums and stir-fry for 30 seconds, then deglaze the wok with shaoxing. Return the chicken and chillies to the wok with the soy sauce, Chinkiang, stock and sea salt and stir-fry until the chicken is cooked through. Add the peanuts and spring onions and stir-fry for 30 seconds, or until the spring onions are bright green. Transfer to a serving plate and discard the chillies before serving.