Begin by removing the extra-firm tofu from its packaging. If it is packed in water, thoroughly drain all the excess water.
Wrap the tofu blocks in a clean kitchen towel or several layers of paper towels. Press gently to remove some of the excess moisture.
Place a light weight, such as a dinner plate, on top of the wrapped tofu blocks for at least 5 minutes.
Pressed tofu should be sliced into roughly 32 cubes (16 cubes per block), each about 1-inch in size.
Preheat the oven to 400º Fahrenheit.
Mix cornstarch, panko breadcrumbs, and garlic powder in a bowl.
Gently coat the tofu cubes in the mixture using your hands, ensuring even coverage.
Line a sheet pan with parchment paper and spread the coated tofu evenly across it.
Bake in the preheated oven for 40 minutes.
While the tofu bakes, prepare the bang bang sauce by combining vegan mayonnaise, sriracha, sugar, and salt in a bowl. Add water if needed to achieve the desired consistency.
Once baked, toss the crispy tofu cubes in the sauce until well-coated.
Serve over rice or alone, garnished with red pepper flakes and chopped chives or scallions.