First thing first, prepare Chili-Horseradish Dipping Sauce. Take a bowl and add mayonnaise, sour cream, horseradish sauce, prepared chili sauce, and cayenne pepper in it. Mix them well to incorporate the ingredients into one another. When the sauce is ready, cover it and place it in the refrigerator. Allow to chill until ready to serve.
In a deep fryer on a large stockpot, add the canola oil. Heat it to 400 degrees Fahrenheit.
Take a large mixing bowl. Add flour, pepper, sugar, paprika, and garlic powder in it. Mix them to make the seasoned flour mixture. Make sure to stir everything well so that all the seasonings are evenly mixed in the flour.
Peel the onion. Then slice it ¾ inches off the root end. Then make almost 16 slices of the onion. But make sure that you are not completely cutting the onion. Just leave an inch from the opposite end of the root. Then remove an inch of center petals from the onion.
Place the onion in the seasoned flour mixture. Toss it to coat the flour mixture on the onion. To let the flour incorporate deeply into the onion, peel the petals slightly. But do not separate or remove them. Just move them enough to let the seasoned flour get in.
Take another mixing bowl. Add flour, beer, paprika, salt, pepper, cayenne pepper, garlic salt, garlic powder, and cornstarch in it. Whisk them to make a smooth batter.
Take the onion you floured in the seasoned flour, and dip it in the batter. Then take out and let the excess batter drip off. Place the onion in a fryer basket. Place it in the heated canola oil. Cook each side for 90 seconds flipping regularly to let the other side fry.
Line a plate with a paper towel. Place the fried onion in it. Let the excess oil drain off. Then transfer the onion to the serving plate.
Add the chilled chili horseradish dipping sauce to a cup. Place it in the center of the onion. Delicious Texas Roadhouse Cactus Blossom is ready. Bon Appetit!