Let stand chicken thighs (hita ng manok) at room temperature for 15 minutes before cooking. While waiting, start preparing your ingredients. Cut your bell peppers (paminta) into one-inch squares and slice the onions (sibuyas) into wedges. Mince your garlic (bawang) and ginger (luya). Set all vegetables aside.
Pat the chicken dry using paper towels and season generously with salt (asin) and black pepper (paminta). Prepare your sauce by combining pineapple juice (katas ng pinya), soy sauce (toyo), chicken broth (sabaw ng manok), and brown sugar (asukal na pula) in a bowl. In a separate small bowl, mix cornstarch (gawgaw) with water (tubig) to make a slurry. Set both mixtures aside.
Heat your pan or kawali over medium-high heat (350°F/175°C). Add cooking oil and wait until it shimmers but is not smoking. Place the chicken skin-side down first and cook for 4-5 minutes until golden brown (hanggang maging golden brown). Turn the chicken over and cook the other side for another 3-4 minutes.
Remove the browned chicken from the pan and set aside. Using the same pan with the chicken drippings (mantika), sauté minced garlic and ginger until fragrant (hanggang mabango), about 1 minute. Add onion wedges and cook until they become slightly translucent, about 2-3 minutes.
Add your sliced bell peppers to the pan and cook for 1-2 minutes until they are crisp-tender. Be careful not to overcook them as they should maintain their bright color and slight crunch. Remove the vegetables and set aside.
Return the chicken to the pan and pour in your prepared sauce mixture. Add the pineapple chunks (pinya) with their juice. Bring to a gentle boil then reduce heat to medium-low (300°F/150°C). Cover and let simmer for 25-30 minutes, occasionally basting the chicken with the sauce (diligan paminsan-minsan ng sarsa).
Check that the chicken is fully cooked by inserting a meat thermometer into the thickest part - it should read 165°F (74°C). You can also cut into the thickest piece; the meat should be white throughout with clear juices (walang pamumula sa loob).
Return the bell peppers and onions to the pan. Give your cornstarch slurry a quick stir (since it may have settled) and pour it into the pan while stirring constantly. Cook for another 3-5 minutes until the sauce thickens enough to coat the back of a spoon (hanggang lumapot ang sarsa).
Turn off the heat and let the dish rest for 5 minutes before serving. This allows the sauce to thicken further and the flavors to settle (para lalong sumarap). Serve hot over steamed rice (mainit na kanin).
For storing, let the dish cool completely before transferring to an airtight container. It will keep in the refrigerator for up to 4 days. When reheating, warm in a pan over medium heat (350°F/175°C) with a splash of water, or microwave in 1-minute intervals, stirring between each interval until heated through.