This version has a very simple, very light tempura style batter. It’s about the simplest batter possible, and I can guarantee that if you cook at all, you’ve already got everything you need in the cupboard.
UPDATE: I’ve also done beer batter onion rings. That one’s a slightly tastier version, but a bit harder to do.
While preparing the onions and batter, set your cooking fat on medium heat to warm up. I prefer beef tallow, but would use lard or olive pomace oil in a pinch. Vegetable oil — corn, soybean, etc. — has too low a smokepoint and turns rancid too easily. Plus it’s not reusable.
While that’s heating up, peel the onion (or onions) and slice into wide rings.
The best onions to use are very large diameter and wider than they are tall. This gives you more large rings than small ones.
When you get to the end with the root, stick a paring knife in at an angle toward the center …
… and spin it around until you get the whole root out.
Pop out the center pieces of each slice that are either not round, or too small to make good onion rings.
Some onions hold on really strong between the layers. If you have one of these, you need to break the layers loose before trying to separate the rings or they’ll all break. Place the ring between your palms, squeeze in enough to make it a little bit oval, and roll it back and forth a few times.
Once it’s loosened up, pop the rings apart, starting from the inside.
Once it’s all separated, one onion makes a surprisingly large pile of rings. I completely underestimated the size of the bowl I’d need to hold it all.
Now mix up the batter — that’s the flour, egg and water — according to the directions in the flounder tempura posting, and salt and pepper. Set your onions and batter up next to the hot fat.
Using metal or high-temperature plastic tongs, dip the rings one at a time into the batter. Make sure each ring is covered all the way around. This batter is very thin, so let the batter drip off for a second before putting it in the fat.
Don’t crowd the pan. Work in batches or they’ll all stick together.
TIP: Use two sets of tongs for this, one to dip the rings and put them in the fat, and the other to turn them over and take them out. You’ll keep the batter cleaner and you won’t get raw batter back onto cooked rings.
Flip the rings over once when they start to show a golden color just above the level of the fat. The second side will be done a little quicker. Don’t set a timer and walk away, this is not an exact process. You need to check frequently so you don’t burn them.
And that’s it.