Drain tofu: place it on a layer of three or four paper towels, top with another layer of paper towels, and press firmly to remove excess water. Cut tofu into 2-inch cubes. Transfer cubes to a baking dish. Add cornstarch, salt, and chili powder, and mix to coat tofu evenly.
Heat about 1 inch of oil in a large saucepan on medium heat. Once hot, carefully add tofu, one cube at a time to make sure they don’t stick to each other. Fry for about 3 minutes. Flip tofu cubes halfway through frying and cook for another 2-3 minutes, or until golden brown and crispy.
Transfer to a plate lined with paper towels to drain excess oil. Set aside.
In a medium saucepan over medium heat, combine all sauce ingredients. Stir regularly until it starts to slightly thicken. Add fried tofu and stir to coat. Sprinkle sesame seeds before serving.
Serve over rice. Add optional toppings such as onions, avocados, cucumbers, and sesame seeds. Serves 2.