Heat a wok until smoking. Add the oil and, when hot, add the ginger, garlic, capsicum, spring onions and duck and stir-fry for 1 minute. Deglaze the wok with the shaoxing, then add the soy sauce, plum sauce, sugar and chicken stock. Bring to the boil, add the bean sprouts and stir-fry for 30 seconds to heat through. Spoon onto a large plate to serve.