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 while you heat the oil.
Using a large deep pot heat your cooking oil to 400 degrees, use a thermometer for best results. Remove the onion from the refrigerator and shake any excess flour from the onion. Using a wire skimmer lower the onion into the oil, cut-side down. Adjust your heat to maintain the oil temperature at 350 degrees.
Fry about 3 minutes, then turn the onion over and cook until golden, about 3 more minutes.
Remove onion using your wire skimmer and drain on a rack placed over paper towels.
Season with salt and pepper, serve with the dip.