Cooking Class: Stir-Frying
Stir-frying is a fast and fresh way to cook. Simply toss and turn bite-sized pieces of food in a little hot oil in a wok over high heat, and in five minutes or less, the work is done. Vegetables emerge crisp and bright. Meats are flavorful, tender, and well seared.
Stir-frying fits hectic lifestyles and health-conscious tastes. It works wonders with September's end-of-season bounty―fresh ingredients such as bell peppers, zucchini, and corn―and because foods cook in a flash, vegetables retain their color and texture. It's a versatile technique you can use every day.
Stir-frying was first developed in China as a cooking method that worked efficiently on simple brick stoves. The typical stovetop had a hole over the fire chamber. A round-bottomed wok fit over the lipped hole, capturing the heat efficiently. All it took was a small, hot fire to make the wok very hot. Oil and chopped food were stirred and tossed in the pan, cooking in minutes and making efficient use of precious fuel.
What stir-frying does
The high temperature required for stir-frying sears food quickly and preserves the natural juices. It takes only minutes (two to five, usually), so vegetables stay bright and crisp, meat browned and succulent. When the heat is high and the cooking quick, the Cantonese describe the result as wok hay―loosely translated "the breath of a wok." It's a difficult quality to define, but you can experience it in the first few moments after food is removed from the wok. The food tastes vibrant and fresh, characterized by concentrated, harmonious flavors with a hint of smokiness. To appreciate wok hay, serve food immediately.
Best bets for stir-frying
Most vegetables cut into thin, bite-sized pieces are ideal, especially those with high moisture content, such as summer squash and bell peppers. Denser vegetables like broccoli work well, too, but may need to either be blanched first or allowed to steam briefly with a little liquid after the initial stir-frying to become tender. Leafy greens such as spinach cook in seconds once they hit the hot oil.
Tender cuts of meat―such as chicken breasts, flank steak, or pork tenderloin―stir-fry beautifully when cut into thin, bite-sized strips. Avoid large or tough chunks of meat from items such as pork shoulder or beef stew meat, which require long, slow cooking to become tender. Shrimp, scallops, and firm-fleshed fish such as halibut work well, but delicate, flaky fish such as flounder or tilapia may fall apart.
All you need for stir-frying are a wok and a broad, curved spatula. A wok, which is shaped like a big, wide bowl with high sloping sides, is designed for stir-frying. The curve of the pan makes it easy for a spatula to scrape down the sides and toss the food without accidentally turning it out of the pan.
The best choice for the typical home cooktop is a rolled carbon steel or enamel-clad cast-iron wok, 14 inches across, with a flat bottom. Carbon steel woks often cost less than 20 dollars at retail stores or online sources, while enamel-clad cast-iron woks are pricier at about $160 or more. (Round-bottom woks may work on gas burners but will not sit steadily on electric ranges.) Over time and with frequent use, carbon steel and cast-iron woks darken and develop a patina that effects a natural nonstick finish (see Caring for your Wok). Avoid pans that come with a nonstick finish, as they can't be used over high heat and the finish deters browning.
In place of a wok, a 12-inch stainless-steel sautée pan with sloped sides can be used. Choose one that conducts heat well. Since these pans don't develop a nonstick patina, they often require more oil for cooking, and food may stick more readily. With the flatter shape and shallow sides of the pan, it's also a bit harder to move the food.
You'll also need a wide spatula. Wok spatulas, shaped like wide shovels, are slightly curved so they can easily slide down the sides of the pan. A lid is helpful for dense vegetables that may need to be briefly steamed at the end of cooking.
When stir-frying, foods must be cut into thin, bite-sized pieces so they'll cook quickly. Generally, they should be of similar shape and size. If the sizes vary widely, foods will cook unevenly.
Mise en place
Stir-frying proceeds at a fast pace and takes attention. The total cooking time may only be five or so minutes, which doesn't allow time to prepare ingredients midstream. Read the recipe through, then cut, measure, and mix ingredients, and set them near the wok. Get out the serving dish. Then turn on the heat.
Choose an oil that can take high heat. An all-purpose, neutral-flavored oil such as canola oil works well. Don't waste expensive extra- virgin olive oil or dark sesame oil for stir-frying. The high heat will diminish the distinctive taste. Use them only at the end or in a marinade to add flavor. Avoid butter, which burns easily at high temperatures.
Preheat the wok on high heat until it is very hot, at least two minutes. It is hot enough to cook on if you see a little smoke rise from the wok, or if you flick a drop of water into the pan and it sizzles rapidly and instantly evaporates. Add oil and rotate the wok so oil coats the surface. The oil will become hot immediately and ripple across the surface.
Stir-fry thinly sliced meat in small batches of six ounces or less, so the pan is not overcrowded―otherwise, you risk a soggy result. With less juicy foods, cornstarch-coated pieces, or thicker pieces such as shrimp, you can sometimes cook up to one pound at a time. Limit vegetables to about four to six cups at a time (or eight to 10 cups for leafy greens). If you use more than one vegetable, add the thickest, densest pieces first, followed by smaller, thinner pieces so everything is done cooking at the same time.
Once the food is in the pan, it needs to be constantly flipped to prevent burning. Use your spatula to efficiently scoop the food.