Prepare the tofu: Cut into ½-inch cubes and soak in hot salted water for 15 minutes. Drain well.
2nd time soaking: Mix baking powder, cornstarch, flour, and water. Soak tofu in this mixture for 5 minutes.
Dry coating: Mix together sweet potato starch, flour (1:1 ratio) and salt. Coat tofu evenly and shaking off excess.
First fry: Heat oil to 175°C (350°F). Fry tofu at medium-low heat for 2 minutes. Drain.
Second fry: Bring the oil back to 175°C (350°F) and fry for another 2 minutes.
Third fry: Repeat the frying process once more to make it extra crispy.
Serve immediately with your favorite dipping sauce!