Step 1: Prepare the Marinade

1. In a medium bowl, whisk together the pineapple juice, soy sauce, honey, rice vinegar, sesame oil, minced garlic, grated ginger, and sriracha (if using).
2. Taste and adjust the seasoning if necessary, adding more honey for sweetness or soy sauce for saltiness.

Step 2: Marinate the Chicken

1. Place the chicken thighs or breasts in a resealable plastic bag or a shallow dish. Pour half of the marinade over the chicken, reserving the other half for later.
2. Seal the bag or cover the dish and refrigerate for at least 30 minutes, preferably 2-4 hours, to allow the flavors to infuse.

Step 3: Prepare the Vegetables

1. Preheat your oven to 425°F (220°C) and line a large sheet pan with parchment paper or aluminum foil for easy cleanup.
2. In a large bowl, toss the bell peppers, red onion, broccoli, and pineapple chunks with olive oil, garlic powder, salt, and pepper. Spread the vegetables evenly on the prepared sheet pan.

Step 4: Add the Chicken

1. Remove the chicken from the marinade and place it on the sheet pan, nestling it among the vegetables. Discard the used marinade to prevent cross-contamination.
2. Brush the reserved marinade (not the one used for marinating) over the chicken and vegetables for added flavor.

Step 5: Roast the Sheet Pan

1. Place the sheet pan in the preheated oven and roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the vegetables are tender and slightly caramelized.
2. For extra browning, broil the sheet pan for 2-3 minutes at the end of cooking, watching closely to prevent burning.

Step 6: Garnish and Serve

1. Remove the sheet pan from the oven and let it rest for 5 minutes.
2. Sprinkle chopped green onions, sesame seeds, and fresh cilantro over the top. Serve the Hawaiian Chicken with rice or your favorite side dish.