Kalimeris Indica.[Photo provided to China Daily]

Intangible Cultural Heritage

In 2015, the skill of making the snack was listed as one of the 41 new Shanghai Intangible Cultural Heritage by the municipal government, alongside other crafts such as paper cutting and comic painting.

But Liu, a former pastry chef, says that making the perfect rice ball requires little skill. Instead, it is all about finding the right ingredient - wild mugwort. At Wang JiaSha, the chefs only use wild mugwort from Ningbo, Zhejiang province.

In contrast, many food factories and snack shops use a powdered form of the plant instead.

This practice is believed to have originated in northern China because the low rainfall in that region during the start of spring means that the plant is not "juicy" enough for use.

Further, using the powder speeds up the process and in turn results in the products having a longer shelf life.

"We are one of the few that use fresh mugwort to make the rice ball. The unique aroma it provides is what makes customers come back for more," says Liu.