01 -  In a large bowl, whisk together soy sauce, pineapple juice, brown sugar, olive oil, garlic, ginger, and black pepper. 
 02 -  Add the chicken cubes to the marinade, tossing well to coat. Cover and refrigerate for at least 30 minutes (up to 4 hours for deeper flavor). 
 03 -  If using wooden skewers, soak them in water for at least 30 minutes to prevent burning. 
 04 -  Preheat your grill to medium-high heat (about 400°F / 200°C). 
 05 -  Thread the marinated chicken, pineapple, bell peppers, and red onion onto skewers, alternating ingredients for color and flavor. 
 06 -  Lightly oil the grill grates. Place skewers on the grill and cook for 12–15 minutes, turning every 3–4 minutes, until the chicken is cooked through and nicely charred. 
 07 -  Serve hot, garnished with chopped cilantro or green onions if desired.