On a rimmed tray, mix the panko, smoked paprika, garlic, onion, cayenne, and salt. In a small shallow bowl, lightly beat the egg.
Preheat the air fryer to 370°F.
Dip each cauliflower floret into the egg, coat with the panko mixture, then place onto a large plate. Drizzle the cauliflower with olive oil and place into the air fryer basket in a single layer with a little space between each floret. Don’t overcrowd the basket. Work in batches if necessary. Air fry for 9 to 12 minutes, or until golden brown and crisp. The exact timing will depend on your air fryer. Repeat with any remaining cauliflower.
Serve with lemon wedges and tartar sauce.