Onion Petals Recipe

Prepare onions

Peel the onions and trim a small slice off the top (stem end) so they sit flat, leaving the root end intact. Place an onion cut-side down. Starting about 1/2 inch from the root, make vertical cuts down toward the root every 1/4–1/2 inch, slicing to but not through the root so the onion falls open into 'petals'. Carefully separate the layers slightly with your fingers so oil and batter can coat each petal.

Dry and refrigerate

Pat the outside of the opened onion dry with paper towels. Place onions on a baking sheet cut-side down and refrigerate uncovered for 15–20 minutes to help them firm up (this reduces slumping when coated).

Make dry mix

In a shallow bowl or wide dish combine the all-purpose flour, cornstarch, baking powder, kosher salt, black pepper, paprika, and garlic powder. Whisk until evenly mixed.

Make wet batter

In a separate bowl whisk together the buttermilk and eggs until smooth. Slowly whisk in the cold sparkling water or club soda until the batter is slightly thin but still coats a spoon (this gives a lighter crisp).

Coat onions — first dredge

Working with one onion at a time, hold it by the root and dredge all over in the dry flour mixture, forcing the flour between the petals so they are well coated. Shake off excess flour.

Coat onions — wet batter

Submerge the floured onion into the buttermilk batter, spooning batter between petals so it gets in between layers. Lift and allow excess to drip off for about 10–15 seconds.

Final coating

Press the battered onion into the panko breadcrumbs on all sides, ensuring breadcrumbs get between petals for a textured, crispy finish. Gently shake off excess panko. Place the prepared onion on a plate or baking sheet. Repeat with the second onion.

Heat oil

Pour vegetable oil into a deep heavy pot or deep fryer to a depth of 2–3 inches. Heat oil to 350°F (175°C). If you don't have a thermometer, test by dropping a small pinch of batter; it should sizzle and float up immediately.

Fry onions

Carefully lower one onion, petal-side up, into the hot oil using tongs or a spider strainer. Fry for 3–4 minutes until the bottom turns a deep golden brown, then carefully flip the onion petal-side down and fry another 3–4 minutes until evenly golden and crisp. Total fry time ~6–8 minutes. If using a smaller pot where oil coverage is limited, you can deep-fry halves or petals instead. Monitor oil temperature and adjust heat to keep at ~325–350°F.

Drain

Remove the onion from oil and place on a rack or paper towels to drain. Lightly salt the onion immediately with a pinch of salt. Repeat frying for remaining onion. Allow cooked onions to rest 2–3 minutes before serving so interior finishes cooking.

Serve

Transfer the fried onion petals to a platter and serve hot with the blooming onion sauce for dipping.

In a small bowl combine the mayonnaise, ketchup, prepared horseradish, smoked paprika, cayenne pepper, garlic powder, salt, and lemon juice. Whisk until smooth and homogeneous. Taste and adjust seasoning — add more cayenne for heat, more horseradish for bite, or a teaspoon of water to thin if needed.

Chill and finish: Cover and refrigerate the sauce for at least 15 minutes to let flavors meld. Stir in chopped fresh parsley just before serving, if using.