2 cups buttermilk
2 cups all-purpose flour
1/2 teaspoon cayenne pepper
salt and pepper
Slice the onions thick and place in a baking dish and cover with the buttermilk and soak 20 to 30 minutes.
Combine the flour, salt, cayenne and black pepper and set aside.
Heat the oil to 375 degrees. dredge onions, in flour mixture, and tap to shake off excess flour.
Fry for a few minutes and remove to a paper-towel-lined plate as soon as they are golden brown.