In a medium mixing bowl, combine pineapple juice, soy sauce, ketchup, sesame oil, rice vinegar, and brown sugar. Whisk until sugar dissolves, then mix in ginger, garlic, and Sriracha. Reserve ½ cup for basting.

Pat chicken dry, season with salt and pepper. Place in a zip-top bag, pour marinade over. Seal and refrigerate for at least 4 hours, ideally overnight.

Preheat grill to medium-high heat (375°F/190°C). Remove chicken from marinade, discard used marinade. Grill chicken skin-side down for 4-5 minutes, then cook on indirect heat for 25-40 minutes, basting every 5-7 minutes, until internal temperature is 165°F (74°C).

For oven method, preheat to 375°F (190°C). Arrange chicken on a wire rack over a baking sheet. Bake for 25 minutes, baste, flip, and baste again after another 15-20 minutes. Total baking time is 45-60 minutes. Broil for 3-5 minutes for crispiness.

Let chicken rest for 5-10 minutes before serving. Garnish with sesame seeds and green onions. Serve with rice, macaroni salad, or grilled pineapple.