Douzhi'er, a stinky bean juice loved by old Beijingers, has plenty of health benefits. 

One man's food is another man's poison. Many people consider douzhi'er, fermented bean juice, as Beijing's most typical traditional drink. But consumers hold radically different opinions about it.

Douzhi'er, made from green beans, goes through several days of fermenting before it is served. Therefore, the smell is not appetizing. But to many old Beijingers, it is their favorite drink and addictive.

It tastes sour at first, reminding one of vinegar, but one will relish the aftertaste of green bean fragrance.

It is said that to the best way to know if one is a Beijinger is to invite him or her to drink a bowl of douzhi'er. If the person frowns and spits the drink, he or she is definitely not a genuine Beijinger. But if the person smiles and finishes it, then he or she is.

Douzhi'er must be accompanied by jiaoquan'er, a crispy ring of dough, and pickle slices.

The fragrant crispy dough ring balances the sour taste of the bean juice, while salty pickle slices complete the combo.

The history of Beijing douzhi'er dates back to the Qing Dynasty (1644-1911). It is said that it was the favorite drink for Manchurians in the Baqi garrison. It was so popular that eventually the Qing emperor and empress dowager both ordered it from the imperial kitchen, to relieve the feeling of greasiness from eating too much meat. Since then what was a cheap drink for the poor became popular also for the rich.

But times have changed. Not only do some tourists find douzhi'er very hard to swallow, some young Beijingers no longer drink it.

The health benefit of douzhi'er could be attributed to the properties in green beans. Chinese medicine believes green beans can dispel heat and have a detoxification function. Douzhi'er is believed to be rich in vitamin C and vegetable protein. The fermentation process might have generated beneficial bacteria too.

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.

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

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.