01 - If using wooden skewers, submerge them in water for at least 30 minutes to prevent burning on the grill.
02 - In a mixing bowl, whisk together the soy sauce, brown sugar, rice vinegar, sesame oil, garlic, ginger, gochujang, and honey until smooth and well combined. Reserve 1/4 cup of the sauce for basting later.
03 - Place the chicken pieces in a large bowl and pour the remaining marinade over them. Toss to coat evenly, cover, and refrigerate for at least 30 minutes or up to 2 hours for deeper flavor.
04 - Thread the marinated chicken, red and yellow bell peppers, and red onion alternately onto the skewers. Brush the assembled skewers lightly with vegetable oil.
05 - Preheat an outdoor grill or grill pan to medium-high heat, approximately 400°F.
06 - Place skewers on the hot grill and cook for 10 to 12 minutes, turning occasionally. During the last few minutes of cooking, brush generously with the reserved BBQ sauce until the chicken is cooked through and slightly charred.
07 - Transfer the grilled skewers to a serving platter. Sprinkle with toasted sesame seeds and finely sliced green onion. Serve immediately while hot.