When you deep-fry something, whether it's homemade onion rings or fish or even chicken, it helps to coat it in some sort of breading or batter, because it helps hold in some of the food's moisture while forming a crispy and golden brown exterior. When a starch like bread or batter turns golden brown, it means that the sugars have caramelized, forming new flavor compounds. In short, golden brown means delicious.
You can go with a breading or a batter, and the right choice really depends on whether you want a more substantial (i.e. crunchy) coating, or one that's lighter and crispier. For crunchy go with a breading, and for light and crispy, you need a batter.
There are a number of ways to achieve a light, crispy batter, and the all involve creating bubbles. As it cooks, the water in the food produces steam, which itself can produce bubbles, and some people like to add a little bit of baking powder to the batter.
On the other hand, the bubbles can also come from the liquid, and you can use seltzer water, which is bubbly, but not very flavorful. Hence beer. I live in the Pacific Northwest, which means I use IPA — which after is what flows out of our faucets in place of water. You're free to use whatever pilsner, lager, ale or stout that suits your fancy.
Another trick is to use cake flour, which is lower in gluten and thus produces a lighter coating than all-purpose flour. I talk about the importance of not overworking the glutens when preparing items such as pancakes and muffins, where you want the end product to be soft and tender. And it turns out that beer batter is no different.
Thus, it's critical that you only mix the flour into the egg-beer mixture until it is barely incorporated. You want it loose and lumpy, just like — well, anyway, that's what you want. And be sure to use COLD beer, because cold helps inhibit gluten development.
Finally, you're going to want to have everything that's going into the batter all ready to go, because once you mix up the batter, you need to use it right away, so that the flour doesn't soak up too much liquid, and also to maximize the fizziness of the beer.
For best results, dredge the item you are going to fry lightly in flour before dipping it in the batter. The batter will stick to the item better this way.
The recipe below will coat 1–2 pounds of onions.
- 1 egg, beaten
- 1 cup cold beer
- 130 grams cake flour (about 1 cup), plus extra for dredging
- ¼ tsp salt
- ¼ tsp paprika
- Combine the egg and beer in a large bowl.
- In a separate bowl, combine the flour, salt and paprika.
- Add the flour to the beer mixture and gently poke at it with a fork until you have a loose, floppy batter with plenty of lumps. Don't stir, whisk or mix! Once the batter is together, dredge and dip your items right away and add to your hot oil.