You can make these ahead and reheat at 400 F (200C) for 3 minutes.
· 1½ cups buttermilk
· ¼ teaspoon cayenne, or to taste
· 2 sweet onions, thinly sliced
· 1 cup all-purpose flour
· Salt and freshly ground pepper
1. Place buttermilk in a dish along with cayenne.
2. Add onion rings and marinate for 15 minutes.
3. Place flour on plate.
4. Season with salt and pepper.
5. Add rings to flour and toss until lightly coated.
6. Heat oil in wok or skillet at 350 F, or until a cube of bread turns brown in 15 seconds.
7. Fry rings in batches, about 2 minutes each batch or until golden.
8. Drain on paper towels and place on cookie sheet.
9. Reheat when needed.