Whisk pineapple juice, soy or tamari, brown sugar, ketchup, garlic, ginger, rice vinegar, vegetable oil, sesame oil (if using), and sriracha/chili (if using). Reserve 1 cup in a clean container for basting.

Add chicken to a resealable bag or shallow dish and pour over the remaining marinade. Seal and refrigerate 4–8 hours or overnight, turning once if possible.

Preheat grill to medium–high (or oven to 400°F/200°C). Clean and oil grates. If baking, line a sheet pan with foil and place a rack on top.

Remove chicken from marinade, letting excess drip off (discard used marinade). Pat chicken dry for better searing.

Grill 6–8 minutes per side, turning often and basting with the reserved glaze after each turn, until caramelized and the thickest piece reaches 165°F (74°C) internal temperature. Move pieces to a cooler zone if they color too quickly.

Oven option: Bake 20–30 minutes (depending on cut), brushing with the reserved glaze halfway. Broil 1–2 minutes at the end to caramelize, watching closely.

Rest chicken 5 minutes. Brush with a final thin layer of glaze, sprinkle with sesame seeds and green onions, and serve with grilled pineapple and rice.

Safety tip: If you plan to use any marinade that touched raw chicken as a sauce, boil it for at least 1 minute before serving.