Put a small dish of water on your table. Working with one wrapper at a time, and keeping the remaining wrappers in the package, place one tablespoon of the shrimp and pork mixture in the center of each circle or square. Using a pastry brush or your fingers, dab a bit of water around the edge of the wrapper. Gather the wrapper up and around the filling, squeezing and pleating it with your fingers to bring the wrapper together like a pouch.
Place the dumplings on a large piece of waxed or parchment paper covered lightly with plastic wrap, and repeat with the remaining wrappers and filling until all the dumplings are formed. You can steam the shiu mai immediately or freeze and steam them later. To freeze them, transfer the dumplings, still on the waxed paper to a cookie sheet and place in the freezer, lightly covered with plastic wrap for 2-3 hours. Put the dumplings in plastic ziplock bags and freeze until ready to steam them.