Slice eggplant, zucchini, tomato, and onion into thin pieces, about 0.5cm thick.
Spread tomato sauce evenly in the air fryer container.
Arrange the sliced vegetables neatly in a circle or in rows.
Drizzle with olive oil and sprinkle with salt and pepper.
Preheat the air fryer to 180°C and cook for 20 minutes.
Transfer the finished ratatouille to a plate and serve.