Step 1: Peel the onions, then carefully slice off the very top (stem end) of each onion, but leave the root end intact. Place each onion root-side up on a cutting board.
Step 2: Using a sharp knife, make 8-12 evenly spaced cuts from the top of the onion down, stopping about 1/2 inch from the root. Be careful not to cut through the root. Gently separate the onion petals to create a 'bloom'.
Step 3: Place the cut onions in a bowl of ice water for 15-30 minutes. This helps them open further and become crispier. While soaking, prepare the batter and sauce.
Step 4: In a shallow bowl, whisk together the flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, salt, and black pepper for the dry mixture. In another shallow bowl, whisk the egg and milk for the wet mixture.
Step 5: For the dipping sauce, combine all sauce ingredients (mayonnaise, ketchup, horseradish, Worcestershire, paprika, garlic powder, cayenne, salt, and pepper) in a small bowl. Stir well and refrigerate until serving.
Step 6: Remove onions from the ice water and pat them thoroughly dry with paper towels. Dip each onion into the wet mixture, ensuring all petals are coated. Let excess drip off. Then, dredge each onion in the dry flour mixture, pressing gently to ensure a thick, even coating on all petals. Shake off any loose flour.
Step 7: Preheat your air fryer to 375°F (190°C). Lightly spray the air fryer basket with cooking oil spray. Carefully place 1 or 2 battered onions in the basket, ensuring they are not overcrowded. Generously spray the coated onions with cooking oil spray.
Step 8: Air fry for 10-12 minutes, then carefully flip the onions, spray again with cooking oil, and continue air frying for another 10-12 minutes, or until golden brown and crispy. Repeat with any remaining onions.
Step 9: Serve immediately with the prepared creamy dipping sauce. Enjoy your healthier, crispy mini air fryer blooming onions!