In a mixing bowl, mix the ground chicken, cabbage, spring onion, ginger, breadcrumbs then add soy sauce, oyster sauce, salt and sesame oil.
Mix it thoroughly until all the ingredients are well combined and refrigerate for 20 minutes.
Separate siomai wrappers individually. Place ½ teaspoon in the center of each wrapper; pat the area surrounding the meat with water; bring the sides of the wrapper up over the meat mixture and press the sides together using your fingertips leaving the meat exposed.
Flatten the bottom part by tapping slowly on a plate for the siomai to stand on its own. Repeat the wrapping procedure until done and ready to cook.
Arrange the wrapped siomai in a steamer. A bamboo steamer is preferred because it gives a natural distinct flavor than using a stainless steel or aluminum steamer.
Make sure that the streamer has at least 3 to 4 cups of water for steaming the siomai but it will depend on the size of the steamer.
Steam for at least 20 minutes and serve.