To make the dipping sauce, add the mayonnaise, sour cream, ketchup, prepared horseradish, sweet paprika, salt, black pepper, and cayenne pepper to a small mixing bowl. Stir to fully combine all ingredients. Transfer the dipping sauce to a small serving bowl and cover with plastic wrap until ready to serve.

Add the vegetable oil to an electric fryer or large 6 to 8-quart pot, and heat the oil to 375°F. The oil should be deep enough in your electric fryer or large pot that the onion is fully submerged while frying. While the oil is heating, you will prepare the onion for frying.

Trim about ½ inch from the top of the onion straight across so that you have a flat, even top. Flip the onion over to the root side and just barely trim off the roots from the onion. Be sure that you leave the root intact. Peel the outer skin from the onion and discard.

Place the onion cut side down (root side up) on a stable cutting surface. Starting about ½ from the root, make a downward cut all the way through the onion until you hit the cutting board. Repeat to create 4 equally spaced cuts around the onion. The onion will be quartered but still held together at the root.

Next, make the same type of cuts in each of the quarter sections to divide the quarter section into halves or thirds. Remember that you do not want to get too close to the root. Repeat until you have made all the additional cuts in the remaining 3 quarters of the onion.

Very carefully flip the onion over, place it onto a large plate, and use your fingers to gently open the sections, creating the “bloomed” onion. The onion should resemble a flower that has “blossomed” or opened up all its petals.

In a medium mixing bowl, combine the all-purpose flour, cornstarch, sweet paprika, garlic powder, salt, and black pepper. Be sure that all the spices are evenly distributed into the flour.

In a separate bowl (big enough that your onion will fit but not too big), add the buttermilk. The amount of buttermilk you will need will depend on the size of the bowl, as the cut onion will need to be dipped or submerged into the buttermilk.

Using your hands, sprinkle up to ¼ cup of the flour over the entire surface of the onion, being sure to separate the onion slices so that the flour gets in between the individual “petals” of the onion.

Carefully pick up the sliced onion, being sure to keep it intact, and dip it into the bowl of buttermilk root side up. You want your onion to be fully submerged in the buttermilk so that the buttermilk can get in between all the individual slices of onion “petals”.

Using a large slotted spoon, lift the onion out of the buttermilk and allow any excess buttermilk to drip back into the bowl. Place the buttermilk-coated onion back onto the plate that you used to add the first batch of flour to the onion. Using your hands, separate the pieces of onion and sprinkle as much of the remaining flour mixture all over the top, sides, and between each of the onion “petals”. You want to get as much of the flour mixture as possible into all the openings so that as the onion fries, the “petals” will all be coated in the batter.

Very carefully, place the battered onion into the basket of an electric fryer or onto a spider. Gently lower the onion into the hot oil and fry for 4-6 minutes or until golden and crispy.

Once the awesome blossom is fully fried, carefully remove it from the hot oil, allowing as much of the excess oil to drip back into the hot pot or electric fryer, then place it onto a paper towel-lined plate to absorb the remaining excess oil.