A true denizen of northern China might scoff at commercial wrappers for dumplings, but really they are so much easier, even for a small batch like this (and before you ask, yes, I can roll my own - albeit slowly). The best and cheapest places to buy wrappers is at shops that make fresh or dried noodles. The skins are available round or square (buy round for this recipe), and often, in two thicknesses. Buy the thicker ones, if you have the choice - they are still quite thin, but the texture is a...