Prepare the onion: Peel the onion and slice off the top stem end, leaving the root end intact. Place the onion root-side down. Make downward cuts from the top towards the root, stopping about 1.5cm from the root. Repeat to create 16-20 evenly spaced petals. Gently separate the petals with your fingers—you should see the layers start to fan out like a flower.

Make the batter: In a medium bowl, whisk together the flour, paprika, cayenne, garlic powder, onion powder, oregano, salt, and pepper. In a separate shallow bowl, whisk the milk and egg until smooth and pale yellow. The mixture should look uniform with no streaks of egg white.

Dredge the onion: Place the prepared onion in the seasoned flour, spooning the mixture between all the petals. Shake off any excess flour until the onion looks dusty but not clumpy. Then, dip the floured onion into the milk and egg mixture, ensuring every petal is coated. Let the excess batter drip off for a few seconds. Finally, return the onion to the flour mixture and coat again, pressing gently so the flour adheres. You should see a thick, speckled crust forming on each petal.

Heat the oil: Pour oil into a deep, heavy-bottomed pot to a depth of at least 7.5cm. Heat the oil to 180°C (350°F). If you don’t have a thermometer, drop a small piece of batter into the oil—it should sizzle vigorously and float to the surface within seconds. The oil should shimmer but not smoke.

Fry the onion: Carefully lower the onion into the hot oil, root-side down, using a spider skimmer or tongs. Fry for 3-4 minutes, then carefully flip the onion over using two forks. Continue frying for another 3-4 minutes. The petals should be deep golden brown and crisp, and you’ll hear a satisfying crackle as the onion cooks. The aroma of fried onion and spices will fill your kitchen.

Drain and season: Remove the onion from the oil and place it on a wire rack set over a baking tray. Sprinkle immediately with a pinch of salt while the crust is still hot. Let it rest for 2 minutes—the steam escaping will keep the centre tender while the outside stays crunchy.

Make the dipping sauce: While the onion rests, stir together the mayonnaise, ketchup, horseradish, vinegar, smoked paprika, and cayenne in a small bowl. The sauce should be a pale coral colour with a creamy, smooth texture. Taste and adjust the seasoning with a little more horseradish if you want extra kick.