Start by slicing the onion. Cut off the top about 1/4 inch and peel the outer skin. Turn the onion cut-side down, and start making vertical cuts all around the onion, being careful not to cut through the root.
Turn the onion upside down and carefully spread apart the petals.
In a large bowl, mix the flour, paprika, garlic powder, cayenne, black pepper, and oregano.
In a separate bowl, combine the eggs and milk, whisking them together thoroughly.
Dip the onion in the egg mixture, ensuring it gets between the petals, then dredge in the flour mixture, again making sure it gets between all the petals. Repeat this step twice.
Heat the oil in a fryer or pot to 350°F (175°C). Carefully place the onion into the hot oil using a slotted spoon.
Allow the onion to fry for approximately 10 minutes, or until it reaches a golden brown color. Remove and drain on paper towels.