1.Combine the sake or rice wine, soy sauce, sesame oil and cornflour dissolved in water. Divide mixture in half.
2.In a glass dish or bowl, combine half of the sake mixture with the chicken pieces and toss to coat. Cover dish and place in refrigerator for about 30 minutes.
3.In a medium frying pan, combine remaining sake mixture, chillies, vinegar and sugar. Mix together and add spring onion, garlic, water chestnuts and peanuts. Heat sauce slowly over medium heat until aromatic.