01 - In a mixing bowl, whisk together the pineapple juice, soy sauce, brown sugar, ketchup, rice vinegar, minced garlic, grated ginger, vegetable oil, and black pepper until the sugar dissolves and the mixture is smooth.
02 - Add the cubed chicken to the marinade, tossing to coat every piece evenly. Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or ideally overnight for maximum flavor penetration.
03 - If using wooden skewers, submerge them in water for 30 minutes to prevent them from catching fire on the grill.
04 - Set your outdoor grill or grill pan to medium-high heat and allow it to come to temperature before placing the skewers.
05 - Thread the marinated chicken pieces alternately with red bell pepper, yellow bell pepper, red onion wedges, and pineapple cubes onto the skewers, distributing the ingredients evenly.
06 - Place the skewers on the hot grill and cook for 12 to 15 minutes, rotating every 4 minutes to ensure even charring on all sides, until the chicken is cooked through and reaches an internal temperature of 165°F.
07 - Remove the kebabs from the grill and let them rest for 2 minutes to allow the juices to redistribute. Serve hot.