1. Stir all the sauce ingredients together in a small saucepan, bring to the boil and simmer for 10 minutes or until slightly thickened. Remove from the heat and allow to cool.
2. Cut deep incisions through the skin of the chicken down to the bone of the drumsticks and breasts. Pour the marinade over and coat the meat well, including in all the grooves and under the skin. Cover and marinate overnight in the fridge.