Chop tempeh into chunks, around 2cm wide.
If using the soy sauce and sesame oil, pour both ingredients onto the tempeh. Stir or shake (with lid on) the tempeh chunks so they are well coated.
Put the tempeh into the air fryer basket in a single layer. Air fry for 15 minutes, stirring halfway.
Check that the tempeh is crispy and golden, otherwise air fry for another 2-4 minutes.