Prep the eggplant: Wash and slice the eggplant into 1/4-inch rounds. Keep the slices even so they cook at the same rate.
Optional salting step: If your eggplant is large or you notice many seeds, spread slices on a tray and sprinkle lightly with salt. Let sit 15 minutes to draw out moisture and any bitterness. Pat dry well with paper towels. If your eggplant is fresh and small, you can skip this.
Preheat the air fryer: Set your air fryer to 380°F (193°C) for 5 minutes. A hot basket helps the coating crisp.
Make the breadcrumb coating: In a shallow bowl, mix panko, Parmesan, garlic powder, onion powder, smoked paprika, oregano, salt, and pepper.
Prepare the egg wash: In another bowl, beat the egg with 1 teaspoon water until smooth. For egg-free, whisk 2 tablespoons mayonnaise with 1 tablespoon water, or use unsweetened plant milk with 1 teaspoon cornstarch.
Coat the slices: Brush or lightly spray both sides of the eggplant rounds with olive oil. Dip each slice into the egg wash, let excess drip, then press into the breadcrumb mixture to coat both sides. Shake off any loose crumbs.
Arrange in the basket: Lightly spray the air fryer basket. Place slices in a single layer with a little space between them. Do not stack. Work in batches if needed.
Air fry, flip once: Cook at 380°F (193°C) for 6–8 minutes. Flip, then cook another 5–7 minutes until golden brown and crisp. Thicker slices may need a minute more.
Season and serve: Taste and add a pinch of salt if needed. Serve hot with lemon wedges and your favorite dip.