1: Make the marinade: Place all the marinade ingredients in the food processor except the lime juice, vinegar, and oil. Pulse 3 to 4 times and scrape down the sides. Add the lime juice, vinegar, and oil, and puree. (If the mixture is too thick to pour, add a tablespoon or two of water.)
2: Place the chicken and the onion slices in a resealable plastic bag and pour the marinade over them. Let the chicken and onions marinate in the refrigerator for a minimum of 4 hours, or as long as overnight.
3: Set up your grill for indirect grilling and heat to medium-high.
4: Set up the Trompo: Place the central spit in the middle as per the manufacturer’s instructions and place the rack in the bottom. Start stacking the marinated chicken, onion, and pineapple on the Trompo. Alternate the direction of the chicken. Stack the onion and pineapple after every 3 or 4 pieces of chicken. Finish the stack with onion and pineapple.
5: Place the loaded Trompo in the grill. Add the wood chunks or chips to the coals. Cook until the chicken reaches an internal temperature of 165 degrees on an instant-read meat thermometer, 1 1/2 to 2 hours.
6: Warm the tortillas on the grill for 1 to 2 minutes per side.
7: Slice the chicken directly off the Trompo spit with long downward strokes of a sharp knife, working inward from the outer, crispier edges. Enclose the chicken, onion, and pineapple in a warm tortilla. Top with your favorite salsa, garnish with fresh cilantro and a lime slice, and serve immediately.
