With a chill in the air as winter approaches, there's nothing quite like warming yourself with some of the tasty snacks being served up by Shanghai street vendors.

Served hot and tasting sweet, roasted chestnuts and sweet potatoes are always the two most popular street snacks around Shanghai in late autumn.

This is the time of the year when chestnuts mature and sweet potatoes taste the best because the sugar levels in them are at their highest.

For most Shanghainese, a packet of roasted chestnuts or a baked sweet potato on a chilly day is even more appealing than a steaming cup of hot chocolate, which is why long queues for the osmanthus-flavored nuts or bumping into a hot sweet potato oven-cart is a regular occurrence on the streets.

Generally chestnuts range in price from 16 yuan (US$2.35) to 32 yuan per kilo, depending on quality with those from northern China considered the best, while sweet potatoes cost about 4 yuan per kilo.

Roasted chestnuts

As soon as chestnuts are harvested, cauldrons are set up seemingly on every other street corner as vendors set about roasting them the traditional way, in a huge wok with sand, sugar syrup and osmanthus essence.

The chestnuts begin to look shiny and bright as if a layer of oil has been applied to them and a shovel is used to stir and heat them evenly.

These days, the process is often electrically operated and, as a rule, cauldrons-shaped chestnuts taste the best.

The sugar-roasted chestnuts from the Xin Chang Fa Food Store chain are regarded as the best in Shanghai. When roasted, they look glossy, do not get cracked or burnt, and the shells fall away easily - always an indication of the quality of the chestnuts - revealing the "meat" which is golden, soft and tasty.