Fat-free, herb-seasoned crouton crumbs add texture and flavor to these onion rings without adding hassle -- or fat. In fact, a serving of these rings contains 75 percent less fat and 60 percent fewer calories than a fast-food equivalent. Don't be put off by the nonalcoholic beer: its bubbles help leaven the batter, and its flavor blends right in.
Heat the oven to 450°. Cut the onions into 1/2-inch-thick slices and separate them into rings; reserve the smallest inner rings for another recipe.
In a large, deep bowl, combine the flour, beer, cayenne pepper (if desired), seasoning salt, and pepper and whisk together. Gently fold in the egg whites; the batter should be light and fluffy. Spread the crouton crumbs in a shallow bowl.
Coat 2 baking sheets with 1 tablespoon of canola oil each. Hook an onion ring on your finger and dip it into the batter, shaking off excess. Then dip it into the crouton crumbs and shake off the excess. Place the ring on one of the prepared sheets. Repeat with the remaining onions and batter, placing the smaller rings inside the large ones to make use of every inch of the pan.
Spray the tops generously with canola cooking spray. Bake for 18 to 20 minutes, flipping after 10 minutes, until lightly browned. Makes 8 servings.