Press the tofu for 15 minutes using a tofu press. Alternatively, wrap the tofu block in a paper towel and place it between two plates with the top weighted down with something heavy.
Cut the tofu into cubes (about 1-inch, but any bite-sized pieces will work).
Toss the tofu with 2 tablespoons of soy sauce and 2 tablespoons of rice vinegar. Set aside.
Bake Tofu: Preheat the oven to 400 F (200 C). Line a baking sheet with parchment paper. Toss the tofu with 1 tablespoon of cornstarch, covering all sides. Bake for 20 minutes, then toss the pieces and bake another 5-10 minutes. They should be firm and brown.
Air Fry: Preheat the air fryer to 380 F (195 C). Toss the tofu in 1 tablespoon of cornstarch. Place the tofu in a single layer in the air fryer basket. Air fry 12-14 minutes, tossing halfway between.
To make the sauce, add all the ingredients, except the cornstarch, to a medium saucepan. Mix well and bring the ingredients to a low simmer. Note: the pan needs to be big enough to add the tofu after it’s cooked.
In a small cup or dish, mix 2 teaspoons of cornstarch with 2 teaspoons of cold water. Stir it into the sauce.
Continue simmering the sauce on low, stirring occasionally. If the sauce becomes too thick, turn the heat down even lower while the tofu cooks. You can also add a tablespoon of water.
When the tofu is done, take the saucepan off the heat. Then mix the tofu with the sauce.
Garnish with sesame seeds and/or sliced green onions.