01 - Slice onions into ½-inch thick rings and carefully separate the layers.
02 - In a shallow bowl, combine flour, garlic powder, smoked paprika, salt, and black pepper.
03 - In a second bowl, whisk together eggs and milk until fully incorporated.
04 - Place panko breadcrumbs in a third bowl, creating a three-step breading station.
05 - Dredge each onion ring in the seasoned flour, dip into the egg mixture, then press firmly into panko breadcrumbs until thoroughly coated.
06 - Place coated onion rings in a single layer in the air fryer basket, then lightly spray with cooking oil.
07 - Cook at 400°F for 10–12 minutes, flipping halfway through, until golden brown and crispy. Cook in batches if necessary.
08 - Whisk together mayonnaise, ketchup, Dijon mustard, lemon juice, smoked paprika, salt, and pepper until smooth and well combined.
09 - Serve the crispy onion rings hot alongside the prepared dipping sauce.