Prepare the coals for the grill. The coals should be lit on one side of the covered grill. In a food processor, combine the sauce ingredients and puree until smooth. Season the mixture with salt and pepper. Season the butts with salt, pepper and Essence. Coat the butts with sauce and baste every 45 minutes throughout cookihg. After the coals are ready, about 45 minutes, place the butts on the grill. The butts should not be over any exposed flame. Cover the grill and vent slightly. Slow cook the but for 6 to 8 hours, or until the meat is very tender.