Hong Kong native and Cha’s owner Charlie Lau became a restaurateur because of a hankering. A movie producer by day, Lau came to Shanghai with Ang Lee to film “Lust/Caution,” and was disappointed that Shanghai lacked a proper Hong Kongese cha canting, a casual all-day eatery that serves traditional Cantonese food alongside milk teas and coffee. So he decided to open his own. On the set of “Lust,” a 1930s period piece, Lau was responsible for ensuring the historical accuracy of the costumes, casting and set design, so it’s not surprising that he designed Cha’s with the past in mind. Walking across the restaurant’s threshold transports you to 1950s Hong Kong.

Twenty years ago, lilong, the tiny alleyways and courtyard houses that make up the backstreets of Shanghai, were packed with tiny mom-and-pop restaurants serving longtang cai, alleyway cuisine, to office workers and neighboring residents. But as the city’s construction boom demolished many of these lanes, the longtang dishes went back into grandmothers’ kitchens, only available to those who were heading home for lunch.

You know you’ve picked a good spot to eat when you give the taxi driver the address and he knows exactly what you’re up to. “The place to eat crayfish!” he’s likely to say enthusiastically.