Dear Mr. Know-It-All,
What is this “wok hei” you keep talking about? What’s so good about it? – Wok the Line
In its most romantic translation, wok hei means “the breath of the wok.” It may be the greatest indicator of true Cantonese cooking: that distinctively smoky, singed flavor which permeates every stir-fried bite. At the edge of every mouthful dances a real sense of the heat that’s gone into every ingredient.
To understand how wok hei comes about, you have to understand the wok itself. Your common or garden wok is a shallow parabola made of lightweight carbon steel, beaten thin so that it transfers heat easily—and loses it easily too.
In restaurants, woks are used over huge, incredibly powerful gas burners. The curved bottom of the wok concentrates all of that heat into a small point at the base of the pan. Wok hei comes from the sheer heat of that cooking process: The searingly hot base cooks food at such high temperatures that what are known as “Maillard reactions” take place—the same reactions that make a well-seared steak so fantastic.
Chefs regulate temperature in the wok not by altering the gas supply, but by moving food around the wok. The higher up the sides it’s sitting, the less it’s cooking. By keeping the food moving all the time—stir-frying, if you will—chefs can evenly cook food with just a flick of the wrist. This even stir-fry process means that Maillard reactions suffuse the whole of the dish, imparting that elusive smoky flavor all over.
A well-seasoned wok builds up a patina over the years, with oil and previously cooked flavor compounds all helping to develop wok hei. In the course of cooking, moisture evaporates and the steam causes the oil coating the food to mist into droplets. When those droplets meet the fire licking up the edges of the pan, they blossom into flame—lending even more of that distinctive wok hei edge.
So, can you achieve this at home? It’s not likely, sadly. True wok hei has to be developed at the tremendous temperatures of a professional Cantonese kitchen. A home gas burner will struggle to reach those heights, and you can forget about an electric or induction ring. Their flat surfaces are totally incompatible with the rounded bottom a wok needs to be truly effective. The flat-bottomed wok, meanwhile, is an abomination unworthy of the term “wok” at all.