Lanzhou Jiangshui Noodles (Soured-Broth Noodles)

Jiangshui noodles are hand-rolled or pulled strands dressed with "jiangshui," a sour broth made by naturally fermenting celery, cabbage and other vegetables in wheat broth, then sizzled with scallion, Sichuan pepper and dried chilli; the soup is pale yellow, sour and cool, a traditional summer noodle dish of Lanzhou and the Long region.

Jiangshui has a long history along the Yellow River, a fermented sour broth kept by households to cool the summer and season the winter. Jiangshui noodles are said to have spread through Lanzhou homes under the Qing, and the dry, hot height of the northwest summer made them a household staple, standing alongside beef noodles as a taste of Lanzhou memory.

Best in the height of summer, the cooked noodles are rinsed, bathed in chilled jiangshui and sizzled scallion oil, and served with a side of blistered chillies or stir-fried leek with pork; the bowl is sour, cool and appetite-sharpening, most often a lunch or supper dish.

The naturally fermented sour broth, its place as a cooling summer dish, and the homely habit of pairing it with blistered chillies are the marks of Lanzhou jiangshui noodles.