People in Shanghai often choose to dine on a bowl of refreshing and chewy cold noodles in summer, and it might still be a good choice now when autumnal wind intertwines with lingering summer heat.

But Shanghai cold noodles must obey several "laws of the soul" to be regarded as authentic.

Firstly, they should be flat. Their flatness gives them a touch of ritual, as diners immediately know they are eating cold noodles.

Secondly, their color is yellowish white. However, a dull yellow color might suggest the noodles contain too much alkali. And they should be neither too dry nor too wet. Good cold noodles are also chewy as they contain rich protein.

In the past, chefs used sesame sauce as the noodles' dressing, but gradually they found peanut sauce tasted better. And the peanut sauce should be neither too sticky nor too watery. Other dressings include soy sauce and vinegar. Some restaurants even use pork hock gravy to increase the noodles' tastefulness.

Several drops of chilli oil will dramatically enhance the noodles' taste.

Toppings can include green peppers, wild rice stem and mushroom shreds mixed with thick chilli sauce.

How the noodles are mixed with the ingredients and toppings can also affect the taste. Usually, soy sauce and vinegar come first, then the peanut sauce and chilli oil. Toppings might be added halfway, so a diner can have both the noodles' original taste and the mixed taste.