Place all the marinade ingredients into a medium bowl and whisk to combine.
Place the chicken breasts in a large, resealable plastic bag and pour in the marinade. Press the air out of the bag and seal tightly. Turn the bag several times to distribute the marinade, place the bag in a bowl, and refrigerate for 3 to 4 hours.
Remove the chicken breasts from the marinade and reserve the marinade. Pour the marinade into a small saucepan and boil for 1 full minute.
Prepare the barbecue for direct cooking over medium heat (180° to 230°C).
Barbecue the chicken, skin side down first, over direct medium heat, with the lid closed, until the meat is firm and the juices run clear, 4 to 6 minutes on each side. Baste with the boiled marinade once halfway through cooking.
Barbecue the chicken, skin side down first, over medium heat, with the lid closed, until the meat is firm and the juices run clear, 4 to 6 minutes on each side. Baste with the boiled marinade once halfway through cooking.
