Douzhi (fermented mung bean drink)
Douzhi is the breakfast that divides Beijing. It is the sour liquid left over when mung beans are ground and their starch settles out to make noodles and jelly; left to ferment for a day or two, the grey-green whey turns tangy, a little cheesy and sulphurous. Old Beijingers drink it piping hot at dawn in hutong shops around Qianmen and Huguosi, with a dish of finely shredded salty pickle dressed in chilli oil and crisp fried dough rings (jiaoquan) from the bakery. First-timers often say it smells like stale socks; regulars say it tastes like home. The texture is thin and slightly creamy, the flavour sour, a little bitter and savoury. The common mistake is boiling the soured starch hard: it separates into grey water and sludge. Bring it up slowly, stirring, and take it off as soon as it froths. The ferment makes only a trace of alcohol, well under 1%. Ferment at 20–25 °C; normal signs are fine bubbles, a sour, yogurt-like smell and a grey colour. Discard it if you see fuzzy mould, pink or black patches, a slimy texture or a putrid smell. Chef's tip: save 100 ml of a good batch to start the next one, as Beijing workshops do.
























