Preheat the oven to 400 degrees Fahrenheit. Line a large, rimmed baking sheet with parchment paper to prevent the tofu from sticking.
To prepare the tofu: Drain the tofu and use your palms to gently squeeze out some of the water. Slice the tofu into thirds lengthwise so you have 3 even slabs. Stack the slabs on top of each other and slice through them lengthwise to make 3 even columns, then slice across to make 5 even rows.
Line a cutting board with a lint-free tea towel or paper towels, then arrange the tofu in an even layer on the towel(s). Fold the towel(s) over the cubed tofu, then place something heavy on top (like another cutting board, topped with a cast iron pan or large cans of tomatoes) to help the tofu drain. Let the tofu rest for at least 10 minutes (preferably more like 30 minutes, if you have the time).
In a large bowl, add the tofu pieces. Add in soy sauce, sesame oil, vinegar, garlic powder, salt, and white pepper. Gently stir together. Sprinkle over cornstarch and cover with a lid or plate and toss to coat.
Tip the bowl of tofu over onto your prepared baking sheet and arrange the tofu in an even layer. Bake for 25 to 30 minutes, tossing the tofu halfway, until the tofu is deeply golden on the edges. Use as desired.