Next comes the tricky part, in which the pot temperature is rapidly raised to 120 C to continue roasting the tea.

"The first 60 seconds of roasting is the most critical step," he says.

A layer of white fuzz (tea hair) will appear on the green tea leaves. The hair is considered an essential characteristic of the tea and is the main standard for evaluating its quality.

"If you stir-fry them over high heat and don't pay attention, the tea leaves will easily spoil," Zhang says. "It's just like stir-frying vegetables — the rhythm and the temperature of the pot must be coordinated, which requires a lot of experience and skill from the tea maker."

After the cooking is done, the temperature is dropped to 60 C, after which the tea leaves are pressed together in the palm and twisted into balls. While twisting, the leaves are continuously roasted for five minutes, which enhances their aroma.

At the end, Zhang fully dries, and then shrinks the tea leaves.

Zhang amazed everyone present at a recent Duyun Maojian tea demonstration event, as he had all the steps down to a fine art. With the simple tools of an iron pot, a mud stove and firewood, he could finish the whole process of making Duyun Maojian tea, whose production technique was put on UNESCO's intangible cultural heritage list last year.

"Tea leaves picked from the bushes must be processed on the same day, or else the aroma will be affected," he says.

Zhang's family has been making Duyun Maojian tea for four generations.

At the age of 5, he started following his grandfather to pick tea leaves during the day and roast them at night.

"I was not even as tall as the stove, but whenever my grandfather roasted the tea, I would stand on my tiptoes and watch carefully," Zhang recalls.

He then memorized all key operations, such as how to grab, shake, twist, knead and flip tea leaves.

At the age of 12, his grandfather encouraged Zhang to try his hand at the art.

Under his grandfather's instructions, he successfully produced the tea's characteristic white hairs for the first time.