National demand is simmering for a new style of hotpot based on a Hainan delicacy, Li Yingxue reports.

As the temperature in Beijing plummets, people in the capital are naturally drawn to the warmth of a bubbling hotpot. According to on-demand services platform Meituan, the search volume of the keyword "hotpot" in October increased 83 percent over the previous month.

Among the various flavors of hotpot, one stands out, becoming the new favorite of many Beijing restaurateurs, retailers and customers — the dregs vinegar hotpot.

Originated in Puqian town, Wenchang, Hainan province, the spicy and sour dregs vinegar soup is a local traditional street snack with a history of around 500 years, dating back to the Ming Dynasty (1368-1644).

The dregs vinegar is fermented from the dregs of the folk liquor making process. The soup is infused with ingredients, such as chili, garlic and sugar, to make it more flavorful, and is served with different vegetables, seafood and animal offal.

The dregs vinegar soup has a milky orange color, and a touch of red hints at its appetizing spicy and sour flavor.

It gradually developed into a hotpot soup base in Hainan. However, it was not until it was introduced in the first season of the documentary Pot of Fire in 2020 that it gained wider recognition among people across the country.

On the restaurant-rating app Dianping, most of the dregs vinegar hotpot restaurants in Beijing are newly opened, and some of them are still undergoing decoration. Also, some restaurants that used to feature another Hainan delicacy, coconut chicken hotpot, are now launching a two-flavor hotpot that serves both the coconut chicken and the dregs vinegar soups.

Within the category, Lanhaiyi dregs vinegar hotpot is one of the most popular choices in Beijing. With two branches already opened this year, two more are under construction.

Lang Lang, co-founder of the restaurant, recalls that she and her friend decided to open the eatery last August, and they spent a month in Hainan researching and learning more about this local delicacy.

"The taste of the dregs vinegar soup base is new for Beijing diners. Compared to other types of hotpot, it doesn't use much oil, which caters to the healthy eating trend of recent years," Lang says.

From Wenchang and Sanya to Haikou of Hainan province, the duo tasted all iterations of dregs vinegar-based food they could find before they started to develop their own recipe.

"There is no standard for the soup. Each store has its own recipe — some add fried garlic, while others add raw garlic," Lang says. "For Beijing diners, we want our version to have a rich and balanced flavor."

After dozens of rounds of trials, Lang has finally settled on one version that she is satisfied with, which adds shredded seafood. They found a local factory in Hainan to make the soup which takes around a month to produce and is shipped by air to Beijing.

The recipe of the dipping sauce is also developed by Lang and her team. They boil their own soybean sauce in their central kitchen so that the flavor is better matched with their soup.

As for the ingredients that diners can choose for their hotpot, Lang says edible seaweed from Hainan is a must, and she recommends shrimps, sea eel and grass carp, as well as fresh beef slices and the mushroom, Sparassis crispa.

With the recipes finalized, the duo opened their first restaurant in January, which soon became a hot spot for both food lovers and internet celebrities. Their second branch opened in July in a shopping mall, and has also become a popular choice for family gatherings.

According to a report on China's hotpot industry development and consumer behavior monitoring in 2022, issued by iiMedia Research, the market size of China's hotpot industry reached 499.8 billion yuan ($70 billion) last year and is expected to reach 668.9 billion yuan in 2025.

The report said that the hotpot market has entered a stage of "white-hot competition" in which restaurateurs have to occupy a niche category or be innovative in their operations.

Lang is confident that dregs vinegar hotpot will earn its market share as more restaurants specializing in the flavor open in Beijing, and more people get to know it.

As Lanhaiyi becomes more popular among Beijing diners, it has also attracted the attention of shopping mall operators, who are clambering over themselves to entice Lang to bring the brand to their locations. "The retailers are sharp about what is popular among customers, and their invitations are giving us more confidence," Lang says.

She says that they have planned to expand their business nationally, as this niche category is relatively new in many places outside of Hainan. "If we open new branches in other cities, we will update the flavor of our soup base to better fit the preferences of local customers," Lang says.

Jiamai Hainan Rice Noodle Snacks opened in Beijing's Shuangjing area of Chaoyang district in October, and its dregs vinegar rice noodle soon became one of the restaurant's most popular flavors.

One customer, a Hainan native, with the handle "Miss May is going to be a food rapper" on Dianping, comments that the restaurant became a spiritual ballast for her when she is homesick, stating: "My favorite is the dregs vinegar rice noodles. You can't imagine how delicious it is to match the spicy and sour soup with the thin soft noodles and some shrimp!"

Fukuuo paper hotpot in Beijing's Chaoyang district is another new destination in the capital for diners who are interested in something spicy and sour, but with a sweet aftertaste. Its sake lees soup base combines Japanese-style hotpot, which uses a special paper as the container, and a Chinese-style soup base that is made with fermented rice.

The restaurant started to get lines of people waiting for a table after the dine-in business resumed in June, following a temporary closure due to the ongoing COVID-19 pandemic.

According to Liu Zheng, who is in charge of the restaurant, his team has spent months developing the soup base and a homemade chili sauce, which can be added to the soup based on diners' tastes.

"We've tried different combinations of rice in the fermenting process to make sure the soup is not too sour and has a sweet aftertaste. In the end, we found our recipe, which uses seven or eight kinds of rice," Liu says, adding that the chili sauce has also been fermented to take the edge off the spiciness.

Liu says that, for the sake lees soup base, anglerfish, puffer and beef are a good match, and they burst with flavor after boiling in the soup. Regardless, the restaurant still offers a special dipping sauce.

As the hotpot is new to customers, Liu says the servers will usually teach diners the best order in which to boil the ingredients and explain the features of each fresh fish.

Besides restaurants, dregs vinegar hotpot has also caught the attention of retailers. At the end of September, Alibaba-owned grocery chain Freshippo launched a dregs vinegar hotpot in around 300 branches across China, including Beijing, Shanghai, Hangzhou of Zhejiang province, Xi'an of Shaanxi province, and Guangzhou and Shenzhen of Guangdong province.

It didn't take long to get popular, and sales in the second week increased 305 percent over the first, ranking second among all flavors of hotpot base soup on the platform.

According to Zhao Jianjian, who is in charge of Freshippo's hotpot business, the reason that the dregs vinegar hotpot was launched was to save customers the cost of flying to Hainan, enabling them to enjoy the dish at home.

"Compared to Tom Yum Kung and other spicy and flavorful soup bases, the taste of dregs vinegar is simple. It does not take away from the taste of the ingredients boiled in the soup and at the same time, it absorbs some of their freshness and sweetness, turning into a rich soup with layers of flavor," Zhao says.

Zhao says that their team took two months to research and develop the soup base.

After visiting many breweries and tasting a dozen kinds of rice, they finally settled on using the same rice that makes a special sweet flavor liquor in Hunan province.

"To make sure our customers all over China can enjoy the same taste of the dregs vinegar flavor, our team has tried around 200 hotpot meals in two months, often eating four to five hotpots a day," Zhao says.

In Hainan, dregs vinegar is not a vinegar drink and the "dregs" refer to fermented rice. The soup base also includes chili sauce, garlic and red pepper.

According to Zhao, the soup base at Freshippo is pure soup, without any solids, and it has also launched an authentic Hainan flavor mixed sauce to partner with the hotpot.

"The best feature of the mixed sauce is that it can stimulate the freshness of beef, chicken and lamb, and is called 'a universal sauce' by Hainan locals," Zhao says.

Made with sesame, peanut oil, ginger and garlic, the sauce is particularly good when kumquats and chili are added.

Together with the hotpot, Freshippo also launched some fresh meat and fish products that can be boiled in the spicy and sour soup.

Zhao says that the best order in which to enjoy the dregs vinegar hotpot is to drink some of the soup first, when it's boiled, and then add cephalopods, such as squid, octopus, and cuttlefish, followed by shrimps and shellfish. Next, add slices of fresh fish, followed by vegetables.

"Finally, add a bowl of rice to the pot, which turns the soup into a sort of seafood congee," Zhao says, adding that beef and chicken are also often eaten in the hotpot by Hainan locals.

The grass carp slices pair so well with the dregs vinegar that they can be boiled for a dozen minutes without falling apart and stay crispy. Zhao says that about 100,000 boxes of grass carp slices will arrive on the shelves of Freshippo stores across the country from Guangdong every day.