In Praise of the Wok

• Any pot or pan can be used for stir-frying, but the technique developed in tandem with the wok. This curved pan is a brilliant piece of basic engineering. It's designed to squeeze the maximum value from both fuel and cooking fat, two historically costly items. The thin metal of the wok heats quickly, even over a relatively small flame. All the fat in the pan drains continuously from the sides to the rounded bottom, where it's cupped and concentrated directly over the heat, making stir-frying an extremely efficient cooking technique.

Keep it Moving

• The classic French saute technique calls for foods to be tossed by shaking the pan. Stir-frying works much the same way, shaking the wok and stirring foods with chopsticks, a spoon or a spatula. Instead of sitting in the hot oil, as they would in a deep-fryer or saute pan, foods pass through the oil rapidly. They come away with a thin coating of very hot oil which cooks them briefly, then slides back down the pan. After one or two minutes of passing through the hot oil, meats or vegetables are fully cooked. The trick is cutting them to the right size and shape to cook in this time frame.

Everybody's Got an Angle

• That's why most recipes specify that foods -- especially vegetables -- should be cut at a diagonal for stir-frying. Diagonal slices create the largest cut surfaces, exposing more of your food to the hot oil and enabling faster cooking. Meats and dense vegetables, such as carrot or daikon, are often sliced further into julienne. Smaller round vegetables, such as asparagus or green beans, would be impractically small if they were cut into simple diagonal slices. Instead, cooks make use of a special "rolling cut" to expose as much surface area as possible.

Keep on Rolling

• The rolling cut is simple once you've tried it a few times, and creates pieces that are easily grasped with chopsticks or a fork. Lay your vegetable on the cutting board and start by trimming off the end with a diagonal cut. Give the vegetable a quarter-turn or half-turn depending on its size, and make a second diagonal cut. Your cut piece will come away with a straight side from the original edge and two shorter diagonals to absorb heat from the wok and its oil. Repeat until the whole vegetable is cut.