“Fresh handmade foods are beautiful after they are steamed, but many are made in factories now,” Chui says.

Younger chefs are less interested in the hard graft it takes to prepare dim sum, he adds – it is usually eaten in the morning, so cooks must get up in the night to prepare.

“Young people think being in this industry means no freedom because you have to get up early and the hours are long,” he said.

At Maxim’s Palace in the harbourfront City Hall building – a favourite with locals and tourists – chandeliers sparkle over dim sum diners in the buzzing banqueting hall.

But, like Chui, Maxim’s supervising chef Tang Leung-hung says there is a dearth of young talent to produce its handmade fare.

“The problem with the industry is the manpower. Young people are not willing to join us,” he said.

“Many of them have turned to hotels' western restaurants and sushi restaurants for jobs instead of Chinese ones [with younger people seeing them as more fashionable and with better hours].”

Watch: Uniquely Hong Kong: Dim sum delights 

Once mainly part of a leisurely weekend ritual which could take hours, many dim sum joints in Hong Kong now have a quick-fire approach, including takeaway kiosks inside subway stations.

With demand growing and rental costs high, mass-produced buns and dumplings imported from mainland China are a way to up the volume and cut costs.

But there are those who are actively seeking to prevent a culinary art from dying out.

In the kitchen of Hong Kong’s famous five-star Peninsula hotel, teenagers don chefs’ whites to knead dough and fill intricate parcels as part of the Dim Sum Young Talent Competition, co-organised by Young Post and the hotel.

“We need to attract youngsters to join this trade. Craftsmanship is what is needed,” says Frankie Tang, executive chef of the Penisula’s Spring Moon Restaurant and organiser of the contest.

“We should make people not forget (how to make) dim sum. We should continue to develop this tradition,” said Wu, who won HK$25,000 cash and a one-year apprenticeship at the hotel.

There is also hope among the city’s food experts, who say dim sum’s enduring popularity at home and increasing appeal abroad will inspire young chefs.

Several of the city’s local dim sum restaurants have received international accolades, including Michelin stars.

“The tradition (of eating dim sum) is still thriving... On Father's Day, for example, you don't go to a western fast food restaurant, you go to yum cha,” says Hong Kong food blogger KC Koo.

Koo adds that it is important to preserve the handmade tradition as it is a key facet of Cantonese culture.

“I have confidence that there will be new blood as the market is there,” he said.

Back at Sun Hing, the elder Chui’s 48-year-old son Chui Kwok-hing is following in his father’s footsteps.

“I come in at 1:30am. Sometimes I feel like I have migrated to another country as the hours are upside down,” he says of the exhausting routine.

But he sees a reason for waking up in the dark.

“People like to have dim sum in the morning, to be energised with some tea before going to work,” he said.

“I feel happy when people think the food is delicious.”

He adds that he wants to preserve the restaurant’s hard-won reputation, saying: “My dad is already 85 years old but he still works here – as the young generation, we should try to be even better.”