In a medium bowl, mix together all the ingredients except the sunflower oil. Leave to marinate in the refrigerator for at least 2 hours.
Preheat the grill to medium. Lay the marinated chicken on a grill tray in a flameproof dish lined with foil, and baste with the oil.
Once the grill is hot enough, grill the chicken for 15–20 minutes until cooked, turning and basting three times during the cooking process. Serve hot.