In a medium-sized bowl, mix together the pork, prawns, mushroom, soy sauce, ginger, sesame oil, salt, and pepper.
Spoon a heaping teaspoon of the filling into the centre of a wonton wrapper. Lightly brush the sides of the wrapper with egg wash. Squeeze the sides up until the wrapper forms a cup, tucking in the sides and leaving the filling exposed on top. Repeat with the rest of the wrappers. Garnish with pea.
Line 1 or 2 large bamboo steamer with parchment paper. Fit the steamer basket(s) in the wok and pour enough water into the wok until the water line is 1 inch below the bottom of the steamer. Steam the su mai for 12 to 15 minutes, until filling is firm to the touch. Serve with soy sauce, chili sauce, or chili oil.
