Prep the onions: Peel the onions, cut off the tops, and slice each onion into wedges (petals) about 3/4-inch thick. Separate the layers so you have individual petals.
Make a soaking station: In a bowl, whisk eggs and buttermilk.
This helps the coating stick and softens any sharp onion bite.
Set up the dry mix: In another bowl, mix flour, panko, garlic powder, smoked paprika, onion powder, salt, pepper, and cayenne if using.
Coat the petals: Dip onions into the wet mixture, letting excess drip off. Dredge in the dry mix, pressing gently so the coating adheres.
Preheat the air fryer: Set to 375°F (190°C) for 3–5 minutes. A hot basket gives better browning.
Arrange and spray: Place coated petals in a single layer in the air fryer basket.
Don’t overcrowd. Mist generously with oil spray for even crisping.
Cook the first side: Air fry for 6–8 minutes until lightly golden.
Flip and finish: Carefully flip petals, spray again, and cook 4–6 more minutes. They’re done when crisp and golden with tender centers.
Season and serve: Sprinkle with a pinch of salt while hot.
Squeeze a little lemon over the top if you like, and serve with your favorite dipping sauce.