In a bowl, combine the mayonnaise, sour cream, ketchup, horseradish, paprika, salt, garlic powder, dried oregano, black pepper, and cayenne pepper. Mix well, cover, and place in the refrigerator to chill.

Cut off about ½ inch from the top of the onion and thoroughly peel away the outer skin.

Place the onion cut-side down on a cutting board.

Using a sharp knife, make a downward cut about ½ inch from the root, repeating this process to create four evenly spaced cuts around the onion.

Turn the onion over and allow it to rest for about 5 minutes, gently separating the outer pieces to create a blooming effect.

Make three additional cuts between each section, totaling 16 cuts without cutting all the way through.

In a large bowl, whisk together the flour, paprika, cayenne pepper, cumin, thyme, and oregano.

In a medium bowl, whisk together the eggs, milk, and 1 cup of water.

Place the onion cut-side up in a clean bowl and pour the flour mixture over it, ensuring the flour gets into the petals.

Carefully turn the onion over and pat off any excess flour.

Place the coated onion into the egg mixture, then return it to the flour mixture for a second coating, patting off any excess flour.

Preheat your air fryer to 350ºF for about 10 minutes.

Remove the onion from the refrigerator and generously spray with cooking oil.

Create a sling from aluminum foil and carefully transfer the onion cut-side up into the fryer basket.

Set the timer for 25 minutes, spraying the onion with cooking oil 2-3 times.

Remove the onion using the aluminum foil sling and season with salt and pepper to taste.

Serve the blooming onion warm alongside the prepared dipping sauce.