Gyoza wrappers are round. If you can't find them, use wonton wrappers and cut them into circles with a biscuit cutter.
Combine all of the ingredients except for the wrappers, peas, and carrots.
Put a tablespoon of filling in the center of each wrapper.
Bring the sides of the wrapper up around the filling, leaving the top open. Squeeze lightly around the dumpling to make a waistline, and flatten the bottom so the dumplings sit flat. Top each dumpling with one pea or carrot.
Line the bottom of a bamboo steamer with cabbage leaves and place the sui mai on top of the leaves. Place the lid on the bamboo steamer.
Heat water to boiling in a wok to a level just below where the bamboo steamer will be. Add the bamboo steamer and steam the siu mai for 15 to 20 minutes. Remove from heat and serve immediately.