Wudu Pounded Potato Mash 武都洋芋搅团

How it is made

The Lanzhou Morning Post (兰州晨报) sets out six steps: wash, boil, peel, cool, pound and dress. The boiling is judged closely: too little water scorches the potatoes and too much leaves them watery, so they start over a high flame and finish on a low one once about 70 percent cooked. They are peeled while hot and spread out on a board.

The cooked potatoes then go one at a time into a purpose-made wooden trough, where they are worked with a wooden mallet until sticky and then pounded hard. It takes two people in rhythm, one dropping in potatoes and one swinging the mallet, and a full batch needs several people taking turns. A skilled pounder makes little noise and gets a supple paste, while brute force is loud and leaves it loose. The paste is ready when it is elastic and no longer sticks to the trough, and it is scooped into a basin. Makers insist on local potatoes, and the paper describes those from Longnan's high mountain areas as large and starchy.

How it is eaten

The Longnan government describes two ways to eat it. Hot, the paste is simmered briefly in suancai jiangshui (酸菜浆水), a sour pickled-vegetable water, and served in that liquid with salt and oil-splashed chilli. Cold, it goes into a broth of boiled vinegar, oil-splashed garlic and chilli.

Diners get a lump of paste in the broth and break off small pieces with chopsticks, dipping each one. It can also be cut up and cooked in the broth, which the paper suggests for older people with delicate stomachs, and leftovers are wrapped in cloth, pressed under a stone and cut into strips the next day to eat cold and dressed. A bowl may come topped with shredded potato, strips of pickled vegetable, chives and chilli oil. The paper calls Wudu's pickled vegetable (酸菜) the essential partner, made from yuangen roots (圆根菜), cabbage, celery and kuju greens (苦苣菜).

Where it comes from

The Longnan government notes that jiaotuan was once food for hard times and has become a well-known local snack. Wudu's version appeared on the documentary series A Bite of China (舌尖上的中国), and on Longnan's snack streets the thud of vendors pounding potatoes carries along the street. Pounded potato mash is eaten mainly in Wudu, in Huating (华亭) and Zhuanglang (庄浪) in Pingliang, and in Lintao (临洮) in Dingxi. Elsewhere in Gansu a dish called simply jiaotuan may be made from wheat, maize or bean flour instead of potato.