Creating Hawaiian Huli-Huli Chicken with Pineapple Glaze is a straightforward process. Just follow these simple steps:

1. Prepare the Marinade: In a large bowl, combine the pineapple juice, soy sauce, brown sugar, ketchup, vegetable oil, garlic, ground ginger, and red pepper flakes. Whisk until the mixture is well-blended.

2. Marinate the Chicken: Place the chicken thighs in a large resealable plastic bag. Pour the marinade over the chicken, ensuring each piece is well-coated. Seal the bag and marinate in the refrigerator for at least 30 minutes or up to 1 hour for deeper flavor.

3. Preheat the Grill: While the chicken is marinating, preheat your grill to medium-high heat. If you are using a charcoal grill, prepare the coals until they are ash-covered.

4. Prepare the Grill Grates: Lightly oil the grill grates to prevent sticking, using a paper towel dipped in vegetable oil and tongs.

5. Grill the Chicken: Remove the chicken from the marinade, letting excess marinade drip off. Place the chicken on the grill and cook for about 6-8 minutes on each side, or until fully cooked (internal temperature should reach 165°F). Brush some of the reserved marinade on the chicken for added flavor during cooking.

6. Grill Pineapple (Optional): If using, place fresh pineapple slices on the grill during the last few minutes of cooking. Grill until caramelized and heated through.

7. Garnish and Serve: Once cooked, remove the chicken from the grill and let it rest for a few minutes. Garnish with sliced green onions and sesame seeds if desired. Serve with grilled pineapple on the side for a wonderful presentation!