Make the Marinade: In a medium bowl, whisk pineapple juice, soy sauce, brown sugar, ketchup, rice vinegar, sesame oil, ginger, garlic, honey, red pepper flakes, and black pepper until the sugar dissolves.
Marinate the Chicken: Place chicken in a zip-top bag or shallow dish. Pour in about two-thirds of the marinade.
Reserve the rest in the fridge for basting. Seal and chill the chicken for at least 2 hours, or up to overnight for deeper flavor.
Preheat Your Cooking Method: Grill: Heat to medium (about 375–400°F). Oil the grates.
Oven: Preheat to 400°F.
Line a sheet pan with foil and set a rack on top if you have it.
Stovetop Grill Pan: Heat over medium to medium-high and brush with oil.
Pat Dry for Better Sear: Remove chicken from marinade and gently pat dry. Discard used marinade. Lightly oil the chicken to help with browning.
Cook and Baste: Grill: Cook thighs 5–7 minutes per side; breasts 4–6 minutes per side, depending on thickness.
Turn every 2–3 minutes and brush with reserved marinade each time you flip.
Oven: Roast 18–25 minutes, flipping halfway. Brush with reserved marinade at the flip and again in the last 5 minutes. For a sticky finish, broil 1–2 minutes at the end—watch closely.
Grill Pan: Cook similar to the grill method, turning and basting often.
Check Doneness: Chicken is done at an internal temperature of 165°F.
The exterior should be glazed and slightly charred at the edges.
Rest and Garnish: Let the chicken rest 5 minutes. Sprinkle with green onions and sesame seeds. Serve with rice and grilled pineapple.