A tiny canteen with a permanent queue out the door, serving what is widely regarded as the best soup dumplings in central Shanghai. Pure pork is the safe choice; crab roe in season is the splurge. They sell out by mid-afternoon — go for lunch. No frills, no menu in English (point at the picture board), no problem.
About 20 RMB for a basket of twelve dumplings. Cash or Alipay. There are a couple of imitators with similar names along Huanghe Lu; this is the one with the dingy interior and the people queuing.