Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1      cup           all-purpose flour
   3      cups          buttermilk
   1      pinch         cayenne
                        salt -- to taste
   4      large         Vidalia onions -- peeled, and
                        cut crosswise into 3/4" slices
   4      cups          peanut oil
   4      cups          all-purpose flour -- seasoned with
                        salt -- to taste
                        freshly-ground black pepper -- to taste
                        ***grilled tomato aioli***
   2                    plum tomatoes -- grilled, seeds and
                        skin removed -- coarsely chopped
   2      cups          good-quality mayonnaise
   3                    garlic cloves -- coarsely chopped
   2      tablespoons   fresh lime juice
   1      pinch         cayenne
                        salt -- to taste

Preparation:

Combine buttermilk, flour, cayenne and salt in a large bowl until smooth. Soak the onion rings in the batter for 2 hours in the refrigerator. Using side burner. Heat oil in a large saucepan to 375F. In batches, remove onion rings from batter and dredge in the seasoned flour mixture. Fry for 3 to 4 minutes or until golden brown. Drain on paper towels and season immediately with salt. Serve with tomato aioli for dipping. Grilled Tomato Aioli: Place all ingredients in a blender and blend until smooth. Season with cayenne and salt. Recipe Source: HOT OFF THE GRILL with Bobby Flay From the TV FOOD NETWORK