Wok hei translated into English means ‘wok thermal radiation’ or, metaphorically, the ‘breath of the wok’. It refers to the flavour and tastes imparted by a hot wok on food during stir frying, and is particularly important for those Chinese dishes requiring searing heat such as Hakkasan’s black pepper rib eye beef with merlot or Wok-fried XO lamb chop. These dishes should have a complex smoky flavour that is only achieved by cooking fresh ingredients over extreme heat, meaning that the flavour develops while simultaneously retaining the textural crunch.
While extremely high heat is necessary, creating wok hei is more difficult than simply raising the flame temperature underneath the wok to extraordinarily high levels. In fact, creating wok hei is so tricky to get right that often it is used as a measure of a Chinese chef’s skill, and these chefs often spend years trying to perfect the art.
In order to achieve wok hei, there are a number of different things to consider:
- The wok should be heated gradually so that it reaches a very high temperature just before the oil, raw vegetables and meat are added. The cooking oil shouldn’t be added until the wok is screaming hot, and then it should be added cold just before the raw ingredients are added. This way, the oil won’t chemically decompose due to the high temperatures.
- The amount of oil added to the wok is important: too much and the food will be fried, too little and wok hei won’t be achieved. The reason a flame ignites is due to the water on the ingredients causing fine oil droplets that mix with the oxygen in the air coming into contact with the flames below the wok when the food is tossed. The flame is necessary for wok hei to create that singed, smoky taste.
- The water in the ingredients, coming mainly from any raw vegetables, is important to achieve wok hei but difficult to manually control. Too much water in the vegetables and they will become soggy in the wok, but too little the food will dry out or burn.
- It’s important not to include too much food in the wok when trying to achieve wok hei. Stir-frying a small amount allows for accurate temperature control and quick stirring.