WHY THIS RECIPE WORKS:
Tasters preferred the gentle flavor of sweet onions to any other kind for our Beer-Battered Onion Rings. After testing many different batters, we settled on a beer, flour, salt, pepper, baking powder, and cornstarch batter. The beer gave the coating flavor, and the carbonation also provided lift to the batter. Baking powder yielded a coating that was thick and substantial, yet light, while cornstarch added crunch to the coating. Before frying our Beer-Battered Onion Rings, we soaked the onions in a mixture of beer, malt vinegar, and salt to soften them and build flavor.

In step 1, do not soak the onion rounds longer than 2 hours or they will turn soft and become too saturated to crisp properly. Cider vinegar can be used in place of malt vinegar. Use a candy thermometer to make sure the oil gets to 350 degrees. Ordinary yellow onions will produce acceptable rings here.

TROUBLESHOOTING BEER-BATTERED ONION RINGS

PROBLEM: Crunchy Onions
SOLUTION: Soak in Beer
Soaking the rings in a combination of beer, vinegar, and salt softens and flavors the raw onion.

MALT VINEGAR
We raided the English larder while making our Beer-Battered Onion Rings for a beloved condiment: malt vinegar. Britons douse fish and chips with the stuff, and given that it’s produced from sprouted barley grains, which are also used to make beer, it made a certain amount of sense for beer-battered rings. Malt vinegar gave the batter a faint, pleasantly malty, yeasty taste. But if you don’t have it, don’t worry. Cider and white wine vinegars are fine substitutions. Avoid balsamic and rice vinegars (tasters found them too sweet for beer batter) as well as red wine and distilled white vinegars (too harsh).

PROBLEM: Bad Battering
SOLUTION: Add Beer Gradually
If the batter is too thick, the rings will be doughy; too thin and it will run off. Add the beer gradually until the batter falls from a whisk to form a ribbon trail.

PROBLEM: Fused Onion Rings
SOLUTION: Don't Crowd the Pot
Fry the battered onion rings in small batches and transfer them one at a time to the hot oil so they don't stick together.