When smelly is good

There is also a set of rules in producing douzhi'er.

The bean drink comes from the process of making green bean starch, when the dried vegetable is ground to powder and mixed with water. In the process, the mixture forms into three layers — the bottom is starch, the top is clear water, and the middle part is what will become douzhi'er.

A bowl of douzhi'er is served with jiaoquan'er, a crispy ring of dough, and pickle slices at the restaurant. Photos by Ye Jun / China Daily

What makes douzhi'er special is the fermentation process. Liu Xushui puts the bean soup into stainless steel buckets, covers it with cloth and leaves it for natural fermentation. He says in summer the process takes one day and two nights, and in winter it usually takes two days and two nights.

The expert chef will then taste to judge if it has the right sourness and proper texture, before sending the drink to the restaurant.

The 52-year-old Liu Chunping uses two bronze buckets to boil douzhi'er. One is a big 35-liter bucket, and another a small 15-liter bucket. The green bean soup is poured into the small bronze bucket, which is put into the big barrel with water in it. The small barrel of bean soup is actually heated by hot water to prevent over heating. The process is similar to double boiling soup.

Each time a chef only pours a small amount of bean juice into the bronze bucket. When it seethes he will pour a bit more inside, until it seethes again. A bucket of bean soup will take between 45 and 50 minutes to boil. During the whole time, the chef will need to stir the soup continuously to prevent the liquid from solidifying.

For that much effort, a bowl of douzhi'er costs only 1.50 yuan (24 cents) at Liu's restaurant.

The restaurant was located at Qianmen Dajie. But it closed down in 2000, when there was a major renovation. Recently Bian Yi Fang Group re-opened Jin Xin near the north gate of Temple of Heaven.

Beijing Time-honored Brands Association has named douzhi'er as the champion in a list of traditional Beijing xiaochi or "snacks". In June 2007, douzhi'er was granted the status of Beijing city level intangible cultural heritage. Liu Xushui, along with 30 other Beijing snack inheritors, has been given the title of "master".