Wok hei: The science behind ‘the breath of a wok’


(CNN) — Chef Kwok Keung Tung tosses the wok with one hand, utilizing the opposite to stir with a steel spatula.

Both fingers occupied, he makes use of his knee to nudge the gasoline range’s lever up and down to regulate the fireplace fan, sporadically engulfing a third of the wok in flames.

It takes solely three minutes for the lump of white rice to remodel into the bowl of golden fried rice he locations on the serving counter.

“This is what you’re looking for — wok hei (the breath of wok),” Danny Yip, co-founder of Hong Kong restaurant The Chairman, tells CNN Travel.

“Wok is the essence of Chinese cooking in South China. And Cantonese chefs are the master of fire and wok.”

Wok hei: An invisible however important ingredient in Cantonese cooking.

Maggie Hiufu Wong/CNN

If anybody’s an authority on the topic of wok hei, it is Yip.

For those that grew up in a Cantonese household, it is virtually not possible to go to a Chinese restaurant with out listening to somebody — often older — remark “gau wok hei” (sufficient wok hei) or “ng gau wok hei” (not sufficient wok hei) when establishing a benchmark of how genuine a Chinese restaurant really is.

Hei (additionally Romanized as “hay”) is the Cantonese phrase for “chi,” that means power stream. It was as soon as a hard-to-explain and largely ethereal idea principally in style within the South China area. In different components of China or Asia, regardless that they used woks, they did not concentrate on wok hei.

It wasn’t till the legendary American Chinese meals author Grace Young coined it poetically as “the breath of a wok” in her ebook “The Wisdom of the Chinese Kitchen: Classic Family Recipes for Celebration and Healing” within the 1990s that the idea of wok hei was launched formally to worldwide audiences.

“Wok hei is not simply hot food; it’s that elusive seared taste that only lasts for a minute or two,” Young wrote.

In different phrases, it is a mixture of that steaming aroma you breathe in and the almost-burning sensation in your tongue that someway enhances the flavors of the dish.

How a wok works

In latest years, an growing quantity of meals writers and scientists have been modernizing Chinese cooking whereas trying deeper into its origins, together with wok hei.

After realizing how little scientific analysis has been performed on Chinese delicacies, Hung-tang Ko, doctoral scholar on the Georgia Institute of Technology, co-published a analysis paper titled “The physics of tossing fried rice” with David Hu — a scientist most well-known for his research on hearth ants and an Ig Nobel Prize-winning investigation into why wombats have cube-shaped poop.

“Wok hei and the Maillard reaction require high heat. The commercial Chinese stoves have a mind-blowing amount of heat coming out of them,” explains Ko, who spent months learning how and why cooks toss fried rice with a wok, whereas additionally simulating rice trajectories.

The Maillard response is a chemical interplay that happens between amino acids and decreasing sugars in meals positioned underneath excessive warmth. It causes meals to brown and releases aroma and flavors.

But why does it should be cooked in excessive warmth and in such a hurry?

“That’s how to extract the maximum wok hei in the shortest amount of time. So the aroma you unlocked from the Maillard reaction won’t escape,” explains The Chairman’s Yip.

Hence, an necessary element of wok hei — aside from the fireplace and the precise wok — is the chef’s tossing ability.

The proper technique to toss a wok

Tossing a wok is a ability that takes time to develop.

A younger chef at The Chairman spends greater than a yr working towards on the wok by cooking workers meals earlier than she or he is allowed to stir fry a dish for patrons.

“Why don’t other chefs use a wok? It’s heavy and the fire can be intimidating and hard to control — now you know why none of the Chinese chefs have any arm hair left,” says Yip, solely half-jokingly.

Why will not stirring suffice? In the case of fried rice, each time it leaves the new wok floor it cools down and avoids getting burnt, as demonstrated within the above video.

“Tossing the wok allows better mixing, which is essential when you have super high heat. Stirring under high heat will likely lead to burning,” says Ko.

During Ko’s analysis, he found that cooks typically pivot their woks utilizing the sting of the range — as an alternative of lifting the complete wok away from the range — to avoid wasting power and improve pace.

Two motions occur concurrently with every toss: “Back and forth pushing and pulling”, and “tilting and rotating the wok back and forth” in a see-saw movement.

So what makes the round-bottomed and extremely conductive wok such a distinctive piece of cooking tools?

“Potentially, other utensils would work, too. But you just need to mix at amazing speeds to make sure that the heat is going into your ingredients uniformly,” explains Ko.

On common, the cooks within the research tossed their wok at a pace of 2.7 occasions per second.

This can also be why many Chinese cooks endure from muscle accidents.

One of the objectives of Ko’s research was to see if it is attainable to create a robotic that would assist cooks toss their wok to cut back the bodily pressure on their limbs. Ko thinks his printed analysis can doubtlessly be utilized in different components of life.

“Can you imagine a laundry drying machine that uses the wok tossing mechanics to toss clothes? My gut feeling is that it will be more efficient — and funnier,” says Ko.

How to make excellent fried rice

Fried rice and wok hei the Chairman

Kwok Keung Tung has been a chef at The Chairman since its opening in 2009.

Maggie Hiufu Wong/CNN

Fried rice was introduced into the highlight in July, due to a viral YouTube video titled “Uncle Roger DISGUSTED by this Egg Fried Rice Video.”

In the clip, “Uncle Roger,” a character created by UK-based Malaysian slapstick comedian Nigel Ng, reacts to a BBC video on the way to cook dinner egg fried rice.

He factors out all the pieces performed fallacious within the authentic egg fried rice video, a response that has gathered greater than 17 million views thus far. Among the foremost offenses within the authentic video? Watery rice.

It’s a problem that sits near the hearts of Hong Kong’s cooks.

“Fried rice and fried beef noodles are the two dishes often used to judge the wok hei of a restaurant,” says Yip. “It is difficult to get each piece of rice or noodle slightly toasted and mixed evenly with the rest of the ingredients without burning it.”

Ko agrees.

“Fried rice is a very symbolic cuisine,” he says. “It is surprisingly hard to make perfect fried rice although it looks really simple. The general principle is to keep it hot — by avoiding putting in watery content that cools the materials down — and mix a lot to prevent sticking and burning.”

Ko suggests utilizing rice that is been cooked the night time earlier than.

“It goes back to the high heat argument. When you put (dried leftover rice) in the wok, the moisture will be minimal … that prevents cooling the wok down or the rice from sticking together,” explains the scientist.

The Chairman, nevertheless, does issues a bit in a different way.

“We know most people use leftover rice as it’s drier. We don’t as we want to keep the inside of the rice moist and retain the most aroma. The trick is to use eggs,” says Yip.

Kwok, the chef, demonstrates.

He first rapidly fries the finely chopped components within the wok, drying them earlier than setting them apart. Then he pours within the oil, egg combination and rice individually.

“Egg dries faster than rice. The chef has to act fast and mix all the ingredients. See, you don’t even see the egg anymore,” says Yip, hurrying this author to take a chew earlier than the aroma escapes.

It’s true. The barely toasted and steaming rice is dry on the floor and every grain is completely coated in golden yellow — you do not see the egg anymore. Each chew of the fried rice remains to be steaming and filled with flavors.

“Taste that?” asks Yip. “This is wok hei.”



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