Mix together the chicken with 1 tablespoon each soy sauce and rice wine and 1 teaspoon cornflour. Leave to marinate for 5–10 minutes.
Heat 1 tablespoon oil in a wok or large frying pan, add the cashew nuts and stir around the pan for 2 minutes until lightly browned, then remove from the pan. Heat the remaining oil and cook the chicken for 5–7 minutes until just cooked through. Remove from the pan.
Add the spring onions, garlic and ginger and cook for 30 seconds, then return the chicken and nuts to the pan, stir in the remaining soy sauce, rice wine and cornflour, the chilli sauce, caster sugar and measurement water. Heat until bubbling and slightly thickened. Serve with boiled rice and wilted watercress.