01 - Peel the onions and trim the root just enough for them to remain upright. Make 4 evenly spaced vertical cuts downwards toward the base of each onion, leaving the base intact. Rotate and make 4 more cuts between the previous cuts. Gently separate the petals with your fingers.
02 - Place onions in a bowl of ice water and soak for 10 minutes to help open the petals. Drain thoroughly and pat onions dry with paper towels.
03 - In a mixing bowl, whisk together the flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, kosher salt, and black pepper.
04 - In a separate bowl, beat the eggs and whole milk together until smooth.
05 - Dredge each onion in the flour mixture, shaking off excess. Submerge in the egg mixture, then dredge again in the flour mixture, pressing the petals gently to ensure even coating.
06 - Fill a deep fryer or heavy-bottomed pot with vegetable oil and heat to 350°F (175°F).
07 - Working in batches, carefully lower onions into the hot oil cut side down. Fry for 2–3 minutes, flip, and continue frying another 2–3 minutes until golden brown and crisp. Use a slotted spoon to transfer fried onions to paper towels to drain excess oil.
08 - In a bowl, combine mayonnaise, ketchup, horseradish, smoked paprika, and garlic powder. Season with salt and black pepper. Mix until smooth.
09 - Serve the crispy mini bloomin’ onions warm with the dipping sauce alongside.