large onion, peeled, sliced 1/4 inch thick, and separated into double rings
Adjust the oven racks to divide the oven in half. Preheat oven to 400°F Spray nonstick baking sheet with nonstick spray.
On a sheet of wax paper, combine the flour, salt, and pepper. Place the breadcrumbs on another sheet of wax paper. Place the egg substitute in a shallow dish.
Coat each double onion ring on both sides with flour mixture, shaking off the excess; dip the onion in the egg, then coat lightly with the bread crumbs. Arrange the rings on the baking sheet and spray the tops with nonstick spray.
Bake on the top oven rack until browned, 10 minutes. Turn carefully and bake until browned, 5 minutes.