Stir-fry is a term that refers both to a style of cooking and a type of dish. The method is quick and uses a minimal amount of oil, and the ingredients are generally simple to prepare. This versatile technique involves quickly cooking bite-sized pieces of vegetables and meat in a wok and finishing with a quick sauce, sometimes thickened with cornstarch or flour. Many popular dishes in Chinese, Korean, Thai, Vietnamese, and Indian cooking are stir-fried, incorporating various proteins including chicken, beef, pork, fish, or tofu and a nearly endless list of vegetables and greens; noodles are often stir-fried as well.
When stir-frying, it's important to do all the prep work in advance. That means peeling (if necessary) and cutting all the vegetables, mixing together any sauces, chopping up all of the meat, and preparing anything else that should be at hand once the cooking process starts. This is because stir-frying is quick — so quick in fact, that there really isn't time to turn away from the stove and do anything else, especially if stir-frying bits and pieces of garlic and ginger, which burn quickly, and this is often the first step in many stir-fry recipes.
While it may seem like stir-frying is all about getting a wok smoking hot, it's probably not practical to expect to achieve the same level of heat on home equipment that a cook would get on a professional-grade stove at a restaurant. Nor is it probably a good idea. (See inset photo at left.) The key here is actually to regulate the heat level and make sure that the ingredients are cut properly and cooked in the correct order. A proper wok helps as well (flat-bottomed ones are recommended since round-bottomed ones… well, we'll let you do the math on that one). (Photo courtesy of flickr/techne)
First things first — make sure you have the right kind of oil. Oils with high smoke points such as canola, safflower, and soybean oil work best. Olive oil is a big no-no since it breaks down and imparts a bitter flavor at high temperatures, which would mar the overall flavor of the dish. And sesame oil is generally used as a flavoring agent at the end, not for cooking.
Next, make sure that all of the vegetables are cut on a bias. This helps maximize the surface area that will be cooked and helps achieve that crisp-tender texture sought after by many cooks. It's also important to preheat the wok before adding the oil. How can you tell if it's hot enough? Sprinkle a drop of water on the wok (preferably prior to adding the oil) and if it goes tssss, it's ready to go. Once the oil is hot, toasting any spices in oil in the beginning will help extract maximum flavor from these sometimes pricey ingredients. (Just don't burn them, or you'll have to start over!)
Earlier, we mentioned cooking the ingredients in the "correct order." This means figuring out which ingredients take the longest to cook since those are the ones that should be added first. Some examples include carrots, celery, firm tofu, broccoli, and bell peppers. Delicate greens and other ingredients that wilt easily, such as scallions, cilantro, or mint should generally be added at the end. Meat should be browned over high heat first, without moving, to develop a flavorful crust. And as always, avoid crowding the pan. Once browned, the meat should be removed from the wok and then added back in to heat through with the sauce when the vegetables are almost done.
The sauce should be cooked with the ingredients to meld the flavors together, and if a thickening agent is used, it should be poured into the center of the wok (with all of the ingredients pushed to the side) and allowed to thicken before mixing with the ingredients.
Lastly, any noodles should be precooked in advance (except for very thin noodles, which will cook with just about ¼-cup water added to the sauce, right before the vegetables are done — reduce heat to medium and cover with a lid until done).