These all-american onion rings can be made easily at home without a deep fryer. Vegetable oil and a heavy-bottomed pan with tall sides is all you need to turn out restaurant-quality onion rings at home!
In another bowl, mix together egg yolks, beer, salt, and butter. Add mixture to flour in mixing bowl and mix to make a thick batter.
Slice your onions into 1/4-inch to 1/2-inch thick slices. Add about 1-inch of oil to a heavy-bottomed pan or skillet. Heat on medium heat until a small amount of batter dropped in fries easily.
In another bowl, beat the egg whites until they form soft peaks. Add the egg whites into the batter and mix gently.
Toss your onion rings in flour to coat, then dip in batter to coat. Gently drop into hot oil and fry, turning once, until golden brown. Drain on a plate covered with paper towels.