Prepare the marinade: In a bowl, whisk together pineapple juice, soy sauce, brown sugar, rice vinegar, ketchup, minced garlic, grated ginger, sesame oil, and red pepper flakes until well combined.
Marinate the chicken: Place chicken thighs in a large zip-top bag or shallow dish. Pour half of the marinade over chicken, reserving the other half for basting. Marinate for at least 2 hours or overnight in refrigerator.
Prepare the grill: Preheat grill to medium heat (about 350°F). Clean and oil grates to prevent sticking.
Grill the chicken: Remove chicken from marinade and place on grill. Cook for 6-8 minutes per side, turning frequently ("huli huli" means turn turn).
Baste and finish: During the last 10 minutes of cooking, baste chicken with reserved marinade every 2-3 minutes, continuing to turn frequently to build up the glaze.
Check doneness: Cook until internal temperature reaches 165°F and glaze is caramelized and sticky.
Rest and serve: Let chicken rest for 5 minutes, then garnish with chopped green onions and serve immediately with steamed rice and grilled pineapple.Retry
