Preheat oven to 400°F (200°C). Line a large sheet pan with parchment paper or foil and spray with extra virgin olive oil spray.
In a small saucepan over medium heat, whisk tamari, pineapple juice, raw honey, tomato paste, 1 tsp EVOO, apple cider vinegar, minced garlic, grated ginger, salt, and pepper.
Mix cornstarch and cold water in a small cup until dissolved, then stir into the saucepan. Simmer for 2-3 minutes until thick and glossy. Divide glaze in half.
Arrange cubed chicken, bell peppers, and red onion on the sheet pan. Drizzle with half of the glaze and toss to coat evenly. Spread into a single layer.
Bake for 15 minutes. Remove pan, add fresh pineapple chunks, and drizzle with the remaining half of the glaze. Toss gently.
Return to oven and bake for an additional 10 minutes until chicken reaches an internal temperature of 165°F.
Switch oven to broil for 2 minutes to brown and caramelize edges.
Garnish with chopped green onions and serve warm over whole grains or cauliflower rice.