The oil tea is a hit among customers at a fair in Hong Kong. CHINA DAILY

"The tea must be gently hammered and firmly pressed, while the heat is carefully controlled to prevent the bottom of the tea pot from burning. The mashing continues until a yellow-green crust forms at the bottom of the pot," Zhou explains.

At this point, hot water is added to extract the tea flavor. "Experienced tea makers will advise you not to add cold water, as this will ruin both the flavor and the appearance of the tea," he adds.

The finished oil tea is best when it has a rich yellow-green color, and has an aroma that is a blend of tea mixed with the scent of scallions and cilantro.

"The tea has a smooth, slightly spicy taste with a hint of bitterness, followed by a lingering sweetness that leaves a memorable aftertaste,"Zhou says.

Over the years, oil tea has become an important part of social interactions for the Yao people, and an expression of hospitality to welcome esteemed guests.

As an increasing number of people from Gongcheng began to work in downtown Guilin, they brought oil tea with them, says Yu Jiajun, head of the Guilin oil tea and food association.

Some oil tea shops have since appeared, Yu adds.

Local authorities launched technical standards for the tea and service norms in 2017 to promote its development. In 2023, more than 1,800 stores across the city sold oil tea, generating around 4 billion yuan($560 million) in revenue, according to the authorities.