Official guidelines have been issued to restaurants across China instructing them how to cook Mao Tse-tung’s favourite meal, an unctuous dish of pork.

According to stringent instructions from the government's food quality supervision and testing institute, true hong shao rou can only be made with the meat of rare pigs from Ningxiang county. Officials have designated the pig, which has been bred for nearly 1,000 years, as an "agricultural treasure".

The Xiaoxiang Morning Herald, a local newspaper, said that three other dishes, including stir-fried peppers with pork, steamed pork with pickled cabbage and steamed fish head with peppers, had also been codified in the official recipe book. Restaurants which do not follow the correct procedures will not be allowed to title themselves as "authentically" Hunanese, said the guidelines.