Press the tofu: Begin by pressing the tofu to remove excess moisture. Use a tofu press or wrap the tofu in a clean towel, placing a heavy object on top. Press for 15-20 minutes.
Cut the tofu: After pressing, cut the tofu into cubes or rectangles (around 1-1.5 inch pieces).
Coat with cornstarch: Place the cornstarch on a shallow plate and coat each tofu piece lightly, shaking off the excess starch.
Air fry the tofu: Preheat your air fryer to 375°F (190°C). Arrange the tofu pieces in a single layer in the air fryer basket. Cook for 12-15 minutes, flipping halfway through, until golden and crispy.
Make the dashi sauce: While the tofu is cooking, combine the dashi, soy sauce, mirin, and sugar in a small saucepan. Heat over medium heat and stir occasionally until it simmers gently.
Assemble: Once the tofu is crispy, transfer it to a serving plate. Pour the hot dashi sauce over the tofu and garnish with chopped green onions, grated daikon, bonito flakes, or sesame seeds if desired.
Serve immediately: Enjoy your delicious, crispy Agedashi Tofu!