- 1 large egg white, lightly beaten
- 1/2 cup well-shaken low-fat buttermilk
- 1/4 cup all-purpose flour
- 1/2 teaspoon salt
- 1/4 teaspoon cayenne
- 1 large sweet onion (12 ounces) such as Vidalia, cut crosswise into 1/3-inch-thick slices
- 1 tablespoon olive oil
- Preheat oven to 450°F.
- Whisk together egg white, buttermilk, flour, salt, and cayenne in a shallow bowl until smooth.
- Separate onion slices into rings and pick out the 12 largest, reserving remainder for another use.
- Heat 1 teaspoon oil in a 12-inch nonstick skillet over moderately high heat until hot but not smoking.
- Working in batches of 4, dip rings into batter, letting excess drip off, then cook in skillet until golden brown, about 1 minute on each side. (Use 1 teaspoon oil per batch.) Transfer rings as browned to a lightly oiled shallow (1-inch-deep) baking pan.
- Bake rings in middle of oven, turning once, until crisp and deep golden, 12 to 15 minutes total.