Chop the onions into round slices 1/4″ (0.5 cm) thick. Separate the parts and roll them in flour. Beat the egg yolks with the flour and beer in a bowl.
To them add the beaten egg whites, salt and black pepper to taste. Heat generous amounts of oil in a pan. Take an onion ring, dip it in the breading and put it in the heated oil.
Stir well and serve the sauce with the breaded onion rings. The perfect appetizer for a cold beer!