01 - Peel onions and trim the root to create a flat base. Cut each onion with four evenly spaced vertical slices from top towards the root, stopping short of cutting through. Rotate and make four additional cuts between each slice. Gently separate the petals without detaching the base.
02 - Submerge prepared onions in ice water for 10 minutes to encourage blooming. Drain thoroughly and pat dry using paper towels.
03 - Combine flour, cornstarch, paprika, garlic powder, onion powder, cayenne, salt, and black pepper in a mixing bowl. Stir until fully blended.
04 - In a separate bowl, whisk eggs and whole milk until uniform.
05 - Dredge each onion in the seasoned flour mixture, shaking off excess. Submerge in the egg mixture, then dredge again in the flour mixture, pressing gently to ensure coating adheres between petals.
06 - Bring vegetable oil to 350°F in a deep fryer or heavy-bottomed pot. Maintain oil temperature between batches.
07 - Fry onions in batches, cut side down, for 2 to 3 minutes. Flip and continue frying for another 2 to 3 minutes, until uniformly golden. Lift out gently with a slotted spoon and transfer to paper towels.
08 - Combine mayonnaise, ketchup, horseradish, smoked paprika, garlic powder, salt, and pepper in a bowl. Mix until smooth and adjust seasoning as desired.
09 - Serve warm bloomin’ onions alongside dipping sauce. Offer additional dipping options as desired.