In a large bowl, mix the soy sauce, brown sugar, gochujang, sesame oil, rice vinegar, garlic, ginger, and black pepper.

Add the chicken cubes to the marinade and toss to coat evenly.

Cover the bowl with plastic wrap and refrigerate for at least 30 minutes or overnight.

Preheat your grill to medium heat.

While the grill is preheating, thread the chicken cubes onto skewers, alternating with the green onions, red bell pepper, and onion.

Once the grill is hot, place the skewers on it and cook for about 4-5 minutes per side or until the chicken is cooked through and slightly charred.

Remove the skewers from the grill and serve immediately.