Fried foods have a mixed reputation at best, because soggy, greasy fried foods are so common. Yet when it's done properly, the foods come out light, crisp and delicate. Proper temperature control accounts for the difference. If you try to fry when the oil is too cool, your efforts are doomed to sodden failure. Ideally, every kitchen would have a suitable thermometer to measure the oil's heat, but that's not always the case. If you're about to fry but have no thermometer, you have a few easy ways to judge whether the oil is ready.
First, Your Eye
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If you're pan-frying in shallow oil, you won't need to begin testing until your eyes tell you the oil is nearly hot enough. It will develop a faint shimmer, and heated oil flows nearly as freely as water. If you hold your hand over the pan, it will feel distinctly warm. With stainless steel or cast iron pans, an even better option is to heat the pan first without any oil in it. When the air over the pan feels hot to your hand, add the oil. It will quickly heat to the correct temperature.
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On most stoves, you'll need to set your burner to roughly a medium-high flame or dial setting to produce the ideal oil temperature, which for most shallow frying ranges from 350 to 400 F.
Then a Tester
At this point, if you're shallow frying, drop in a thin shred of food such as a sliced onion. If it begins immediately to sizzle, your pan is hot enough. If it browns at the edges within the first few seconds -- one reason an onion is the ideal tester -- your pan is already getting too hot, and the oil will begin to smoke soon. Take it off the burner for a few seconds to cool before you add your food.
Some cooks suggest using a kernel of popcorn as a sort of pop-up thermometer, because corn pops at temperatures between roughly 360 and 400 F. While this works, the idea of a hot projectile spraying scorching-hot oil around the kitchen is less than appealing. If you use popcorn as your tester, be sure to cover the pan with a lid or splatter screen. A second complication is that popcorn doesn't always pop, so your best option is to use three or four kernels and scoop out the remainder once that first kernel pops.
Deeper Testing
The onion test works for deep frying as well, but you don't necessarily want that onion taste in your food. Instead, insert a wooden chopstick or the handle of a wooden spoon into the fat. If you see a merry stream of bubbles form around the wood, the oil is hot enough to cook in.
A cube of white bread provides another tool used by cooks. At a normal deep-fry temperature of 350 to 360 F, a piece of fresh bread takes 45 to 60 seconds to brown. A dry crouton or piece of stale bread will require only about half of that time, because of its lower moisture content. If your recipe calls for cooking at 375 to 380 F, as many do, fresh bread will brown in 30 to 45 seconds and dry bread -- again -- in about half that time. In each case, the oil around the bread should bubble vigorously. If it doesn't, you're not ready to fry.
Tips from the Masters
Getting the right temperature is only a starting point. For masterful results, experienced cooks know to observe a few other important rules:
- Don't crowd the pan. Cold food drops the oil's temperature dramatically, which undoes all your good work. Instead of one large batch, fry in two or more small batches.
- Use a high, narrow pot if you don't have a deep fryer. The small surface area means less of your oil is exposed to the air, so it won't oxidize and break down as quickly. It's also a visible reminder not to overcrowd your pan.
- Dry your food thoroughly or coat it. Wet food spits and spatters when it hits the hot fat, increasing the risk of injury. It also creates steam at the surface of your food, which inhibits browning and makes it harder to get that perfectly crisp surface.
- Drain fried foods on a rack or brown paper, rather than paper towels or a clean kitchen towel. Towels retain steam from the hot food and make it soggy.