Soak the mushrooms in hot water for 20 minutes and then slice off and discard stems.
Chop the mushroom caps.
Combine all of the chopped ingredients with the pork, salt, soy, wine, sesame oil and egg white.
Mix well together and put 1-heaped teaspoon of mixture into the centre of each wonton wrapper.
Gather the wrapper around filling and press it close to give the shape of a little moneybag, open at the top.
Press a prawn on top of each for decoration.
Lightly oil a steamer and put the sui mai in a steamer basket.
Cover tightly and steam over boiling water for 20 minutes.
Serve with soy dipping sauce.