It is most often used for stir frying, but can also be used many other ways, such as in steaming, deep frying, braising, stewing, or making soup. It is commonly, almost exclusively, cooked with a long handle chahn (spatula) or/and a long handle hoak (ladle). The long extensions of these utensils allows the cook to maneuver the food without burning the hand.
Standard Mandarin refers to woks using a different character, "guō" or with the phrases "guōzi" (Simplified: 锅子, Traditional: 鍋子), or "chǎo cài guō" (Simplified: 炒菜锅, Traditional: 炒菜鍋). In Indonesia the wok is known as a penggorengan. In Malaysia it is called a kuali (small wok) or kawa (big wok). In the Philippines it is known as a kawali and also called a "wadjang". In Japan the wok is called a chukanabe (literally, "Chinese pot"). In India a similarly-shaped vessel is known as a karahi, and also sometimes referred to as a wok.
The wok's most distinguishing feature is its shape. Classic woks have a rounded bottom. Hand-hammered woks are sometimes flipped inside out after being shaped, giving the wok a gentle flare to the edge that makes it easier to push food up onto the sides of the wok. Woks sold in western countries are sometimes found with flat bottoms - this makes them more similar to a deep frying pan. The flat bottom allows the wok to be used on an electric stove, where a rounded wok would not be able to fully contact the stove's heating element. A round bottom wok enables the traditional round spatula or ladle to pick all the food up at the bottom of the wok and toss it around easily, this is difficult with a flat bottom. With a gas hob, or traditional pit stove, the bottom of a round wok can get hotter than a flat wok and so is better for stir frying.
Most woks range from 30 cm to 2 meters or more in diameter. Woks of 36 cm (14 inches) (suitable for a family of 3 or 4) are the most common, but home woks can be found as small as 20 cm (8") and as large as 91 cm (36"). Smaller woks are typically used for quick cooking techniques at high heat such as stir frying (Chinese: chǎo, 炒 or bao, 爆). Large woks over a meter wide are mainly used by restaurants or community kitchens for cooking rice or soup, or for boiling water.
The handles for woks come in two styles: loops and stick. Loop handles are the most common handle type for woks of all types and materials, and are usually made of bare metal. Cooks needing to hold the wok to toss the food in cooking do so by holding a loop handle with a thick towel (though some woks have spool-shaped wooden or plastic covers over the metal of the handle). Cooking with the tossing action in loop handled woks requires a large amount of hand, arm and wrist strength. Loop handles typically come on pairs on the wok and are riveted, welded or extended from the wok basin.
Stick handles are long, made of steel, and are usually welded or riveted to the wok basin, or are an actual direct extension of the metal of the basin. The handle is sometimes covered or ended with a wooden or plastic hand grip, but it is not uncommon to find a bare metal grip. This handle facilitates the tossing action for cooks used to using western saute pans with similar style handles. These kinds of woks are often referred to as "Peking pans" or "pau woks". Stick handles are normally not found on cast iron woks since the wok is either too heavy for the handle (thick cast iron wok), or the metal is too thin to handle the tensile stress exerted by the handle. Larger woks with stick type handles usually also have a loop on the other side to aid with handling the wok as well as to counter balance the stick type handle.
The most common materials used in making woks today are carbon steel and cast iron. Although the latter was the most common type used in the past, cooks tend to be divided on whether carbon steel or cast iron woks are superior.
Currently, carbon steel is the most widely used material. Steel woks are usually inexpensive relatively light in weight, have quick heat conduction, and reasonable durability. However, carbon steel woks are more difficult to season and the carbonized season is easily removed in newer woks, both making food more prone to sticking to the wok. Carbon steel woks vary widely in price, style, and quality, which is roughly based on ply and forming technique. The lowest quality woks tend to be single ply and stamped straight from a piece of steel. These woks have a higher tendency to deform and misshape. Cooking with them is also more difficult and precarious since they often have a "hot spot". Higher quality woks are almost always "hand hammered" and made of two sheets of carbon steel which are formed into shape by "ring-forming" or hand forging. The real purpose of hand hammering is to create small ridges or dimples along the sides of the wok. These ridges are used in the frying technique of the chef.
Two types of cast iron woks can be found in the market. Chinese cast iron woks are thin (~3 mm) and weigh about the same as a carbon steel wok of similar size, while western cast iron woks tend to be thick (~9 mm), tend to be heavy, and require very long heating times. Cast iron woks are superior to carbon steel woks in heat retention and uniform heat distribution. They also form a more stable carbonized layer of seasoning which makes it less prone to food sticking on the pan. However, both types of cast iron wok also have some disadvantages compared to carbon steel woks. Chinese-style cast iron woks, although quicker in heating and relatively light, are relatively fragile and are prone to shattering if dropped or mishandled. Western-type cast iron woks are slow-heating and slow-cooling, which makes temperature control more difficult. Furthermore, heavy western cast iron makes the tossing action required in stir-frying and bao difficult for smaller chefs.
Non-stick, steel woks coated with Teflon are common in the western market. These woks are easily scratched and cannot be used to cook in the high heat required for stir frying to excess of 230°C (c.450F) since the Teflon coating will break down chemically at these temperatures. At 350°C (660°F) the burning coating produces vapours which, if inhaled, can cause flu-like symptoms (see Teflon flu). Xylan coated woks are slightly more robust, but still cannot be used for very high heat cooking. Less commonly found are clad woks, which sandwich a thick layer of aluminum or copper between two sheets of stainless steel. These woks perform extremely well but are often quite expensive, quite heavy and usually cook no better than carbon steel or cast iron woks. Their biggest advantage lies in the durability and ease of maintenance of a stainless steel exterior and cooking surface. Many of these vessels are dishwasher safe.
Woks can also be made from aluminium. Although an excellent conductor of heat, aluminium does not retain heat (heat capacity) as well as cast iron or carbon steel. Although anodized aluminium alloys can stand up to constant use, plain aluminium woks are too soft and damage easily. Aluminium is mostly used for wok lids.
Typically a small amount (1-3 tablespoons) of peanut oil, soy oil, sunflower oil, or canola oil is placed in the wok and heated under full burner heat. (Alternatively, first heat the wok, when it smokes then add the oil) Fresh chopped garlic and ginger are often added to the oil to flavor it, then quickly scooped out before burning or turning brown. The first item to be cooked, for example, sliced meat, is stirred in the very hot oil until hot, then pushed up the side of the wok so as to drain off the oil while continuing to cook. The meat may be returned to the oil and pushed to the sides several times until the cooking is done. The hammered ridges or dimples along the side of the wok "grab" and prevent the meat from slipping back into the oil at the bottom of the wok.
Once cooked, the meat is often scooped out with a Chinese strainer to a side plate and the next ingredient such as vegetables are then cooked in the same manner, strained out or held against the side while any leftover cooking oil is thrown out before all of the ingredients are typically thrown back together, with sauces, seasonings, liquids, corn starch mixed with a little water for thickening, stirred and covered for a final heating for a minute or two or until smoke begins to escape from the cover. This way the chef controls the length of cooking for each item and the food does not cook sitting in the oil.
Woks by design are meant to be used over a pit-style stove, where the heat arising from the fuel is fully directed at the bottom of the wok, with no heat escaping around the edges. These pit stoves originally used wood or coal, but are now more typically a gas stove that has burners that are recessed below the stove's surface, to encompass the wok's shape. Curved grates on the stove provide stability to the curved wok. This allows foods to be stir-fried at a very high heat, sometimes hot enough to deform the woks themselves. Pit stoves are typically used by professional chefs in most Chinese restaurants, since they have the heating power to give food an alluring wok hei.
Traditionally-shaped woks can be used on some western-style (flat-topped) gas stoves by removing a burner cover and replacing it with a "wok ring," which provides stability and concentrates heat. Although not as ideal as "pit stoves", these allow woks to be used in a manner more suitable for their design and are good enough for most tasks required in home cooking.
Because of the high cost of these kitchen modifications, coupled with increased heat and smoke generated in the kitchen, more and more home chefs are using their wok outdoors on high-heat propane burners with curved wok support grates. Many inexpensive propane burners are easily capable of 60-75,000 Btu or more, easily surpassing most in-home gas stoves.
Woks, be they round or flat bottomed, do not generally work well for stir-frying or other quick cooking methods when used on an electric cooker. These stoves do not produce the large amounts of quick even heat required for stir-frying. However, it is possible to find round-shaped electric stove elements that will fit the curve of a wok, which allows the wok to be heated at its bottom along with part of its sides. A flat-bottomed wok may also work better on an electric stove.
Coupled with the lower heat retention of woks, meals stir-fried on electric stoves have a tendency to stew and boil when too much food is in the wok rather than "fry" as in traditional woks, thus not producing wok hei. However, a wok can benefit from the slow steady heating of electric stoves when used for slower cooking methods such as stewing, braising, and steaming, and immersion cooking techniques such as frying and boiling. Most Chinese cooks use cast-iron pans for stir-frying on electric stoves, since they hold enough heat for the required sustained high temperatures.
A newer trend in woks is the electric wok, where no stove is needed. This type of wok gets plugged into an electrical outlet and the heating element is in the wok itself. Like stove-mounted non-stick woks, these woks can also only be used at lower temperatures than traditional woks.
The main advantage of wok beyond its constructed material is its curved concave shape. The shape produces a small, hot area at the bottom which allows some of the food to be seared by intense heat while using relatively little fuel. The large sloped sides also make it easier for chefs to employ the tossing cooking technique on solid and thick liquid food with less spillage and a greater margin of safety. Curved sides also allows a person to cook without having to "chase the food around the pan" since bite-sized or finely chopped stir-fry ingredients usually tumble back to the center of the wok when agitated.
The curve also provides a larger usable cooking surface versus western-styled pots and pans, which typically have vertical edges. This allows large pieces of food seared at the bottom of the wok to be pushed up the gently sloped sides to continue cooking at a slower rate. While this occurs another ingredient for the same dish needing high heat is being cooked at the bottom. The pointed bottom also allows even small amounts of oil to pool. As such large food items can be shallow fried, while finely chopped garlic, hot peppers, green onions, and ginger can be essentially deep-fried in both cases with very small amount of cooking oil.