Combine all the TSUYU SAUCE ingredients in a small saucepan.
Simmer over medium heat until it's reduced by ⅓. You should have about 1 cup of sauce remaining.
Cover and place on a back burner on low heat to keep warm.
Frying the Tofu
Begin by removing moisture from the tofu. Sandwich the tofu between a few sheets of paper towels. Place a plate on top of the tofu with something to weigh it down, such as canned vegetables. Let it drain for 15-20 minutes.
Heat 1" of oil in a pot to 350°F. While the oil is coming to temperature, cut the tofu into 6 pieces (about 1.5" blocks) and dry with fresh paper towels.
Once the oil has reached 350°F, it's time to dredge the tofu. One at a time, roll the tofu in potato starch on all sides until it's fully coated. Gently dust off any excess starch until a light coating remains. It's important to fry the dredged tofu immediately so the coating doesn't get soggy.
Carefully place the dredged tofu into the hot oil and fry on both sides until it's lightly golden. To avoid overcrowding and bringing down the temperature of the oil, fry in small batches.
Remove the tofu from the oil and place on a wire rack to drain the excess oil.
Serve Agedashi Tofu immediately in small bowls and carefully pour Tsuyu Sauce into the side of the dish to maintain the crispy coating. Top with grated daikon, grated ginger, dried bonito flakes, and scallions.
Notes
It's very important to fry the tofu as soon as possible after it's been dredged in potato starch. The tofu continues to release moisture and will get soaked up by the potato starch and turn gummy.