Combine pork or chicken, mushrooms, ginger and garlic making sure they are very finely chopped and mixed evenly. Add sesame oil, sherry, soy sauce, 5 spice powder, salt and sugar and blend. Lastly add the egg white.
Spread cooked rice on a shallow dish. Using wet hands, shape the pork mix into 1/2-inch size balls. Roll in the rice to cover. Place pork balls in a bamboo steamer, cover and steam over a saucepan of boiling water for 8-10 minutes.
Arrange all the lettuce leaves on a large serving plate. Place the pork balls on the leaves with soy sauce on the side for dipping.