Soak mushrooms in hot water until they are soft-about 20 minutes. Drain, rinse in warm water and drain again. Squeeze out as much water as you can. Remove stems and discard. Finely chop caps. Mix mushrooms, pork, bamboo shoots, scallions,egg white, cornstarch, salt, soy sauce, sesame oil and white pepper.
Cut the corners from wonton skins to form a circle. Keep the skins covered with plastic wrap to keep them from drying out. Place one tablespoon of filling into the center of skin and bring sides up, forming a little cup. Repeat until the filling and/or skins are finished. Keep filled dumplings covered with plastic wrap to keep them from drying out.
Place the dumplings in a single layer on the rack of a steamer. (I use a bamboo steamer) You will have to do this in a couple of batches. Cover and steam over boiling water for about 20 minutes. Watch that the water does not boil away and add water if needed.
Dipping sauce-mix the ingredients together in a tiny dipping bowl.