1Preheat your oven to 400°F (200°C). Line a large sheet pan with parchment paper or lightly grease it.
2In a small saucepan, combine the pineapple juice, soy sauce, honey, rice vinegar, sesame oil, garlic, and ginger. Heat over medium heat until the mixture begins to simmer. In a small bowl, mix the cornstarch with water to create a slurry. Stir it into the sauce and cook for 1–2 minutes until the sauce thickens. Remove from heat and set aside.
3Arrange the chicken breasts or thighs in the center of the sheet pan. Surround the chicken with the pineapple chunks, bell peppers, and red onion. Drizzle the olive oil over the vegetables and toss them to coat. Season everything with salt and pepper.
4Brush half of the Hawaiian sauce over the chicken and drizzle the remainder over the vegetables. Toss the vegetables lightly to coat them evenly.
5Roast in the preheated oven for 25–30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the vegetables are tender and slightly caramelized. For extra caramelization, broil the sheet pan for 2–3 minutes at the end of the cooking time.
6Sprinkle sesame seeds and chopped green onions over the chicken and vegetables for garnish. Serve warm over steamed rice, cauliflower rice, or noodles