01 - In a mixing bowl, whisk together the soy sauce, pineapple juice, brown sugar, ketchup, minced garlic, grated ginger, and rice vinegar until well combined. Reserve 1/4 cup of the marinade and set aside for basting later.
02 - Place the chicken thighs in a large resealable plastic bag or shallow bowl. Pour the remaining marinade over the chicken, ensuring each piece is evenly coated. Seal and refrigerate for at least 20 minutes, or up to 2 hours for deeper flavor penetration.
03 - Heat a large skillet over medium-high heat. Remove the chicken from the marinade, discarding the used marinade. Sear the chicken thighs for 4 to 5 minutes per side until a golden-brown crust forms and the meat is nearly cooked through.
04 - Transfer the chicken to a plate and set aside. In the same skillet, add the sliced red and yellow bell peppers, red onion, and pineapple chunks. Stir-fry for 4 to 5 minutes until the vegetables are slightly softened but still retain a crisp-tender texture.
05 - Return the seared chicken to the skillet with the vegetables. Pour in the reserved marinade and bring the mixture to a gentle simmer. Stir in the cornstarch slurry and continue cooking for 2 to 3 minutes, tossing to coat everything evenly, until the sauce thickens to a glossy glaze.
06 - Serve the Hawaiian chicken hot, garnished with sliced green onions and toasted sesame seeds. Pair with steamed jasmine rice or cauliflower rice for a complete meal.