One of my favourite snacks when I'm in Shanghai is sheng jian bao. Often called soup dumplings, these are very different from the other (and more popular) version, xiao long bao. While the latter have a thin wrapper and are steamed, sheng jian bao are made with a leavened dough and cooked in a skillet with a lid, so the bottoms of the dumplings are pan fried, making them brown and crusty, while the tops steam and become slightly puffy. After being sprinkled with sesame seeds and spring onion, sheng jian bao are eaten with dark vinegar.
How a dumpling comes to be filled with broth remains a mystery to many. As with xiao long bao, the filling for sheng jian bao is pork based. The meat is mixed with a broth that has been cooked with pig skin or other ingredients that have a lot of natural gelatin. When the broth cools, it solidifies. It's then chopped into small pieces and combined with the meat and seasonings before being wrapped. When the sheng jian bao are pan-fried, the gelatin melts and turns into soup.
There's an art to eating these dumplings that stops the hot soup from squirting up your nose or all over your clothes or companions: carefully bite into the top of the dumpling, suck out a little of the juice and then let the hot steam escape before eating the rest of it.