01 - Slice the onions into ½-inch thick rings. Separate into individual rings and set aside.
02 - In a shallow bowl, combine flour, garlic powder, paprika, salt, and black pepper. In a second bowl, whisk together eggs and buttermilk. Place panko breadcrumbs in a third bowl.
03 - Dredge each onion ring in the flour mixture, then dip into the egg mixture, and finally coat thoroughly with panko breadcrumbs.
04 - Arrange the breaded rings in a single layer in the air fryer basket. Spray lightly with cooking spray. Air fry at 400°F for 10–12 minutes, flipping halfway, until golden brown and crisp. Work in batches if necessary.
05 - Mix mayonnaise, ketchup, Dijon mustard, lemon juice, smoked paprika, cayenne, salt, and pepper until smooth. Refrigerate until ready to serve.
06 - Serve the crispy onion rings hot with the dip on the side.