Firstly, wrap your tofu in a few sheets of paper towel after draining it. Rest a heavy pot on top of the tofu to press it for about 15 minutes - this will remove the excess moisture from your tofu.
Then, mix canola oil and cornstarch in a small bowl, and whisk vigorously until the cornstarch is evenly dissolved in the oil.
Break your tofu block up into medium bite-sized pieces using your hands, and then cover it in the oil and cornstarch mixture.
Put the tofu into the airfryer basket at 400 degrees for 15-30 minutes until it is a deeply golden brown color, shaking the basket halfway through the cooking process.
Notes
Keep in mind that air fryers vary in shape and size which can greatly affect the cooking time for your tofu- this is why the range is between 15 and 30 minutes. I recommend checking the tofu around 7-10 minutes into the cooking process to see how it's doing and determine how much longer you need to air fry it. At the halfway point, the outside of the tofu should look somewhat dried, and shaking the air fryer basket should easily move the tofu pieces around. If the tofu is still sticking to the basket instead of flipping, it probably needs a few more minutes before you can flip the tofu.