Hotpot (or huǒ guō) is a pot full of boiling water in which you throw pieces of vegetables, meat and fish and will eat served with different sauces. You will find hotpot in all China with, of course, some regional variations (e.g. Sichuan hotpot is probably more spicy). When in Shanghai I would recommend Plantain & Rain Hotpot restaurant, which serve Australian beef.
Plantain & Rain, 919, Tianshan Lu, 3rd floor. 919 天山路，919号，3层。021－56128777
Wuji Spicy Hotpot 吴记老锅底