Oh, all those years spent eating (and enjoying!) onion rings made from white or sweet onions. Not wasted years, but years of missed opportunities of eating spicy red onion rings.
Heat 2" of oil to 350 F in a deep fryer or Dutch oven.
Whisk the buttermilk and hot sauce together in a pie plate.
In another pie plate, combine the flour, cornstarch and salt.
Working in batches, dip rings in buttermilk, then flour. Repeat.
Transfer to fryer in batches. Do not overcrowd. Fry for about 2 minutes, flip and fry another 2 minutes or until golden brown. Transfer to a paper towel-lined plate and sprinkle with salt.
Serve with dipping sauce.
For the dipping sauce
Whisk together all ingredients.
Notes
For a little extra spiciness, let the rings marinate in the buttermilk/hot sauce mixture for 1 hour before battering and frying.