Slice onion in very thin strips from top to bottom. Can do this very early in the day and just cover with cold water in the ice box. Then at least one hour before dinner place in a dish and soak in buttermilk for at least one hour.
Combine dry ingredients and set aside. Heat oil to 375 degrees. Grab a handful of onions, shake around in the seasoned flour and shake off excess. Now you kind of need to make sure they are separated as you drop them in the hot oil.
Deep fry for a few minutes till golden, and place on paper towels to drain for a few seconds and I have found to keep them warm and crispy, place them on top of a cake cooling rack over baking pan and place in 200 degree oven. Want t make sure hot air can circulate under them also.
Notes: One of the easiest ways I have found to bread these things is to take a colander, roll a big handful around in it then put them in the colander and shake it around to get rid of the excess flour. Also if you like a bit more spice than just cayenne pepper then put a few drops of Tabasco in your buttermilk mixture.
To make an easy fry sauce I mix 1/4 cup Miracle Whip, 1/4 cup Ketchup, 1 teaspoon crushed garlic, 1 teaspoon lemon juice, 1 teaspoon grated onion, a couple of shakes of hot sauce and on occasion a touch of horseradish.