Put the flour into a bowl and make a well in the center. Pour the beer into the well and whisk until the mixture is just combined. Strain the batter through a sieve into a clean bowl and let it rest, covered, for 1 hour.
Dust the onion rings with the additional flour, shaking off the excess, and coat them with the batter. Working in batches, fry the onion rings in 2 inches of preheated 370 degrees, oil until they are golden. Transfer them with a slotted spoon to paper towels to drain and sprinkle them with salt to taste.
Recipe courtesy of Gourmet Magazine