In a small saucepan over medium heat, combine the tamari, maple syrup, pineapple juice, garlic, and ginger.
In a small bowl, make a slurry with the cornstarch and water, whisk until the cornstarch is completely dissolved.
Slowy pour the slurry into the saucepan, stir continuously.
Bring to a boil and allow to boil for 2 minutes, until the sauce begins to thicken. Remove from heat and set aside.
Cut the tofu into 1x1" cubes and place in a shallow container. Pour the Teriyaki Sauce over the tofu until it is completely covered in sauce.
Alllow to marinate in the refrigerator for 1 hour.
Preheat the oven to 450° F. Line a baking sheet with foil and set aside.
Evenly build the skewers with tofu, onions, bell peppers, and pineapple. Each skewer gets 3 pieces of tofu.
DO NOT THROW AWAY THE TERIYAKI MARINADE, we will brush the skewers with this at the end.
Bake for 30 minutes, turning each skewer every 10 minutes to get them to cook and brown evenly.
Remove from the oven and brush them with the left over teriyaki marinade.
Serve immedietely. ENJOY!!