Slice the onion to make it bloom. Start by cutting off 1/2 inch from the top of the onion, then peel the outer skin from the onion.
Place the onion cut-side down. Starting about 1/2 inch from the root, make a downward cut all the way through to the cutting board. Repeat to make four evenly spaced cuts around the onion.
Turn the onion over and set aside for 5 minutes to allow the petals to relax. Prior to breading, use your fingers to gently separate the outer pieces.
Make 3 additional cuts between each section until you have 16 evenly spaced cuts.
Whisk the flour, paprika, cayenne, cumin, thyme, and oregano in a large bowl. In a medium deep bowl, whisk the eggs, milk, and 1 cup water.
Place the onion in a clean bowl, cut-side up, and pour the flour mixture on top. Using a large spoon to coat the onion with the flour mixture, especially between the onion petals. Turn the onion over and pat off the excess flour. Reserve the bowl of flour.
Transfer the onion into the egg mixture and coat evenly. Remove and let the excess drip off, then transfer back into the reserved flour mixture and repeat the flouring process.
Place the onion into the refrigerator.
Preheat the air fryer for 10 minutes to 350ºF.
Remove the onion from the refrigerator and spray generously with cooking oil (vegetable or olive).
After making a sling from a sheet of aluminum foil, transfer the onion cut side up into the fryer basket.
Set the timer for 25 minutes and cook. Spray the onion with the cooking oil 2-3 times as you cook it fully.
Remove onion using the aluminum foil sling and season with salt and pepper.
Serve with the dip.