Preheat an air fryer to 400 degrees F (200 degrees C). Spray the basket of the air fryer with cooking spray.

Pour egg in a shallow dish. Mix cornmeal, flour, panko, salt, and pepper in a second shallow dish. Dip each tomato slice in egg and then coat both sides in cornmeal mixture.

Place tomato slices in a single layer in the prepared basket and lightly mist the tops with cooking spray.

Cook in the preheated air fryer for 8 minutes. Flip tomatoes and spray any dry spots with cooking spray. Cook 4 more minutes and transfer to a paper towel-lined plate. Repeat with remaining tomato slices.