Prep the Oven and Ingredients: Preheat the oven to 400°F. Chop the carrots, zucchini, onion, broccoli, and pineapple.
Make the Teriyaki Sauce: Heat a small saucepan over medium heat. Combine coconut aminos, sesame seed oil, garlic, and ground ginger. Stir well. Once the mixture begins to boil gently, stir in the tapioca flour mixture. Reduce the heat to low and allow the sauce to thicken. Once thickened, remove from heat.
Cook the Chicken: Spray a clean sheet pan with non-stick cooking spray. Place chicken breasts on the sheet pan and brush generously with the teriyaki sauce, reserving some sauce for later. Bake the chicken for 15 minutes.
Add the Veggies and Pineapple: Remove the sheet pan from the oven and arrange the carrots, zucchini, onion, broccoli, and pineapple chunks around the chicken. Drizzle the reserved teriyaki sauce over the veggies, saving a little for finishing.
Finish Baking: Return the sheet pan to the oven and bake for an additional 20 minutes, or until the veggies are tender and the chicken reaches an internal temperature of 165°F.
Serve and Store: Drizzle the remaining teriyaki sauce over the chicken. Garnish with sesame seeds and serve with cauliflower rice, if desired. Store leftovers in an airtight container in the fridge for 3–4 days.