Upmarket restaurant Bai Le Tian Hotpot Restaurant.[Photo by Tang Yingzi/China Daily]

Though people now eat spicy Chongqing hotpot all year round, even in summer, the chilly winter offers more reasons to enjoy the mouthwatering delicacy.

This strongly-flavored and oily local dish has gained huge popularity in recent years, especially since the release of the food documentary A Bite of China four years ago. It seems like there are Chongqing hotpot restaurants in every Chinese city, though most people in northern and coastal regions never used to eat chilies.

Boasting both the best and largest number of hotpot restaurants in the country, Chongqing was named "China's hotpot city" by the China Cuisine Association in 2007.

According to the Chongqing Hotpot Association, there are more than 50,000 hotpot eateries, employing at least 3.5 million people.

Although there is no hard evidence as to how it originated, many believe the hotpot emerged from porters' cuisine in the late 19th century.

Chongqing is a port city surrounded by the Yangtze and Jialing rivers. In the late 19th century, animals from Sichuan, Guizhou and Yunnan provinces were shipped by water. Good meat was shipped and sold to the upper and middle classes. The internal organs, including stomach and kidney, were discarded or sold cheaply. Porters picked up or bought the organs and cooked them in a boiling pot with a spicy sauce and ate it by the water.