"It was like wanting an iPhone, except people could eat it," Lu recalls, referring to the restaurant where he worked, Zhuang Yuan Lou, as the "Apple store" of its day.

Although it was not the only place offering pickled cuisine, people were more than ready to wait for hours outside the one and only "Apple Store", which didn’t open until 4 pm.

"It has something that is missing from what is sold in other places," says Lu Yongchun, a 57-year-old Shanghai housewife, who says she has fed her family Zhuang Yuan Lou’s cuisine for decades.

Chef Lu sums up what he thinks is the missing ingredient.

"People always think it’s all about the sauce. I am not saying that the sauce is not important, but the way you preserve the food in the sauce is also crucial," he says.

Lu’s way is to freeze the food for a while before dipping it into the sauce, so that the original taste of the food remains, or is highlighted by the light alcoholic flavor of the sauce.

While it is believed "everything that can be put into mouth can be dipped into the sauce", the best sellers are always meat and animal organs.

"Both the sauce and the food, usually overnight leftovers, are nowadays considered unhealthy and unfresh, or in Chinese, ‘the terrible dross’, but they are loved and enjoyed every summer by millions for a reason. They taste great," Lu says.

He says he has never seen or heard of a single case of stomach trouble resulting from eating the pickled sauce, and he believes that’s because around 20 types of Chinese traditional medicinal herbs are used in the sauce.