In a mixing bowl, combine garlic powder, onion powder, char siu sauce, Sriracha, pineapple juice, dark soy sauce, and salt. Add chicken thighs to marinade. Refrigerate for at least 2 hours or up to 1 day.
Pre heat oven to 375F
Line rimmed baking pan with aluminum foil.
Remove chicken thighs from marinade and arrange chicken skin side up. Discard marinade mixture.
Cook for 10 minutes. Flip the chicken thighs skin side down and cook for 10 minutes. Then flip chicken again, back to skin side up, and cook until the skins are evenly browned (with a little bit of charred color on top), approximately 5 minutes.
Transfer cooked chicken thighs to serving platter, garnish with cilantro or green onion and serve hot immediately.