Press the tofu if you haven't already - see note. Cut it into cubes.
Pour the marinade into a plastic zip top bag: 2 tablespoons soy sauce, [2 tablespoons pineapple juice and ½ inch] of fresh peeled ginger. Add the cubed tofu and mix around so it's all covered with marinade. Place in the fridge for at least 30 minutes.
Preheat the oven to 400°F. Line a baking sheet with parchment paper and set aside.
When the tofu is done marinating, remove the tofu and place in a single layer on the prepared baking sheet. Bake for 25 to 30 minutes, flipping each piece half way through the cooking time.
In the meantime, whisk together the stir fry sauce: tomato paste, 3 tablespoons soy sauce, 2 tablespoons pineapple juice, maple syrup, and vinegar. Mix together the cornstarch and water and add to the sauce. Whisk well and set aside.
Heat a large skillet with 2 tablespoons water (or broth) over medium-high heat. Add the garlic and ginger and sauté for about 3 minutes until fragrant.
Add the carrots and ¼ cup water (or broth), cover and let cook about 5 to 7 minutes. Check every few minutes and add more water/broth if the pan is getting dry. Add the snow peas, water chestnuts, scallions and pineapple chunks and cook another 2 to 3 minutes.
Add the stir fry sauce and mix well. Add the baked tofu and mix again.
Serve over rice and garnish with sliced green onions, sesame seeds and a sprinkle of sesame oil, if desired.