To butterfly chicken breasts, place breasts on a cutting board. Using a sharp knife, cut almost through each breast horizontally, starting at the thick end of the breast, leaving about 2 cm along the long end of the breast uncut. Open the breast like a book and flatten with your hands. This will allow the chicken to cook quickly and evenly.
Put all the ingredients, except the chicken breasts in a food processor and blend until smooth. Put the marinade in a freezer bag or a large dish. Add the breasts, turning them to evenly coat. Refrigerate for at least 2 hours, or overnight. Preheat the barbecue to medium and grill the chicken for 3 - 4 minutes on the first side, but just 2 minutes on the second side. Serve with rice and whatever is fresh from the garden.