Make seasoning sauce: Combine all the seasoning sauce ingredients in a skillet. Heat over medium high heat, stirring for about 1 to 2 minutes until bubbling. Remove from the heat and set the skillet aside.

Coat the tofu: Cut the tofu into 1 x 1½ inch bite sized pieces. Pat dry with kitchen towel or paper towel. Gently put the tofu into a plastic bag and add the potato starch. Seal the bag and gently turn it over until the tofu is well and evenly coated with the starch. Remove each piece from the bag individually and transfer to a large plate or a cutting board lined with plastic wrap, leaving some space between the pieces.

Fry the tofu: Heat the oil in a skillet for 5 minutes, until it reaches 330-340°F. Carefully add the tofu pieces one at a time to the hot oil. Turn the heat down to medium and let the tofu cook for about 2 to 3 minutes, until the bottom turns light brown and the surface is a little crispy. Turn the tofu pieces with tongs or a slotted spoon—they should be firm enough to turn without breaking—and fry for another 2 to 3 minutes, occasionally turning so that all sides turn light brown and crispy. Remove from the skillet and set in a wire mesh strainer set over a bowl.

Reheat the oil for 1 minute over medium-high heat and fry all the tofu again for 3 to 4 minutes, rotating and turning them over with tongs or long wooden chopsticks, until all sides are golden brown and crunchy. Transfer the tofu to the strainer set over a bowl to drain the excess oil.

Handle pumpkin seeds: If you use pumpkin seeds, put them into a slotted spoon and dip them into the hot oil to fry them for just 10 seconds or so. Transfer the seeds to a small bowl and turn off the heat.

Coat and serve: Reheat the sauce in the skillet until bubbling. Add the fried tofu and gently mix all together until they are well coated. Transfer to a plate and sprinkle the pumpkin seeds over top. Serve as a side dish for rice.