Prepare breading station: On plate 1, place 1/4 cup vegan mayonnaise. On plate 2, combine 1/2 cup panko breadcrumbs, 1 tsp dried oregano, 1 tsp dried basil, 1 tsp granulated onion, 1 tsp vegan parmesan, a pinch of salt, and a dash of pepper. Plate 3 is for breaded eggplant.
Coat eggplant slices: Use fingers to apply a thin layer of mayo to each eggplant slice. Coat all slices before moving to the next step. Add more mayo as needed (up to 1/4 cup).
Bread eggplant slices: Dip each mayo-coated slice into the breadcrumb mixture, ensuring full coverage. Place breaded slices on plate 3. Add remaining panko and seasonings if needed.
Air fry eggplant: Arrange eggplant slices in a single layer in the air fryer basket. Do not overcrowd. Spritz tops with oil spray. Air fry at 400°F for 12 minutes, flipping halfway and spritzing with more oil.
Add toppings and finish: At the 10-minute mark, add a spoonful of marinara sauce and a pinch of vegan mozzarella to each slice. Continue cooking until browned and melted. Remove.
Toast buns: Heat a dry skillet to medium. Place burger buns face down to toast the cut sides until nicely browned. Remove from heat.
Assemble sandwiches: Top bottom burger buns with a few slices of vegan eggplant parmesan, fresh basil leaves, and thin slices of yellow onion. Top with remaining buns.
Serve immediately and enjoy your crispy vegan eggplant parm sandwich!