Like french fries, most people would rather buy onion rings than prepare them.
That makes it much easier to offer the best recipe for home fried onion rings without fear of contradiction. Try telling people what the best recipe is for fried chicken or mint julep and see how many arguments you get!
There seems to be general agreement about preparation of fried onion rings, either for home consumption or in a restaurant: the onion rings should be soaked in cold milk and/or water before frying. It crisps them up. Rather like putting parsley in a plastic bag with the water left from rinsing it to perk it up.
The usual rules for deep fat frying apply to onion rings -- about having enough fat and having the fat hot enough; about not crowding the food to be fried and thereby reducing the temperature; about having a batter of the right consistency so it won't slide off the food, especially the slippery skin of the peeled onion. Too rich a batter will do that and you are left with bits of fried batter bubbling around in the fat and limp, naked onion rings.In addition, the richer the batter the more fat it will absorb during frying.
After frying one batch of food allow the temperature to return the required heat before adding more rings. Skim out any bits of batter after each batch is finished. Make sure the surface of the food to be fried is as dry as possible. So after crisping the onion rings in milk/water, dry them off with paper towels before dipping in the batter. You can test the "adherability" of the batter by holding it in a spoon over the bowl. It should not run from the spoon in one long band. Rather, it should drop in successive "splats." You can never be sure if you have added the proper amount of flour, so adjust it if necessary. Batter should be refrigerated at least two hours. It can also be held overnight.
If, after trying the best of Washington's commercially prepared fried onion rings you know you can do better at home, try this recipe adapted from the "Joy of Cooking." You can use red or yellow onions: the red are much sweeter. Fried Onion Rings (4 servings) 2 large yellow or red onions l cup milk l cup water 1 1/3 cups flour Salt and pepper to taste 1 tablespoon cooking oil 3/4 cup stale beer 2 beaten eggs
Skin the onions and cut crosswise into l/4 inch thick slices. Combine the milk and water and soak the onions in this mixture for l hour. Drain. Spread rings on absorbent paper and dry well.
In the meantime mix together flour, salt, pepper, oil and eggs. Stir in the beer. Allow the batter to rest at least 2 hours, or as long as over- night in the refrigerator.
Heat enough cooking oil to 350-370 degrees in deep, flat-bottomed pan so that the rings will be completely covered. Separate the onion slices into rings (one or two rings can be fried as a single piece). Dip several rings in the batter, using a long handled fork with only two tines. Hold rings above the batter to allow excess batter to drip off. Place only enough rings to fit comfortably in the pot without crowding. (You can also use a deep fat fryer basket which can be submerged and lifted out of the hot oil.) Fry rings until they are a light golden brown. Drain well on absorbent paper and serve immediately.
There is no such thing as a good reheated or leftover fried onion ring.