In a mixing bowl, combine buttermilk or the milk and lemon juice mixture. Let it sit for about 5 minutes to thicken slightly.

Peel two medium sweet onions, then carefully cut off the tops and bottoms. Make vertical cuts from the top down to form blooming petals.

In another bowl, whisk together flour, paprika, garlic powder, onion powder, cayenne pepper, salt, and pepper.

Dip each prepared onion into the buttermilk mixture, letting any excess drip off before transferring to the flour mixture.

Preheat your air fryer to 380°F (190°C) for about 5 minutes.

Place the coated onions in the air fryer basket, being careful not to overcrowd them.

Lightly spray the tops of the onions with cooking spray or oil.

Cook the onions in the air fryer for 10-12 minutes, shaking the basket halfway through.

While the onions are cooking, mix together mayonnaise, ketchup, horseradish sauce, lemon juice, and preferred seasonings in a small bowl.

Once the blooming onions are crispy and golden, remove them from the air fryer and serve warm with the dipping sauce.