Preheat the air-fryer to 400 F. In a shallow dish, whisk egg and milk together. In another shallow dish, place flour. Combined cornmeal and breadcrumbs in another shallow dish.
Coat each green tomato slice in the egg mixture, then coat in the flour, coat back into the egg, then coat in the cornmeal and breadcrumb mixture.
Air-fry in batches for 10-12 minutes.