Heat the sunflower oil in a large wok or frying pan, add the red onion and pepper and stir fry for 1-2 minutes.
Add the garlic, chilli and chicken to the onion mixture and cook over a very high heat for about 4 - 6 minutes, or until chicken is sealed and tender.
Add the spring onions to the wok and cook for another minute. Place the cornflour in a small bowl and add the black bean sauce, sherry and water. Whisk until well combined. Add the sauce mixture to the wok and allow to thicken slightly.
Serve with boiled or steamed rice.
