Rinse the pre-soaked dried mushrooms then put them together with the seasoning (A) in a small saucepot. Bring to a boil, then simmer for 2025 minutes. Drain the mushrooms, cut off the stalks and leave aside to cool completely.
Put minced pork, prawns, water chestnuts and seasoning (B) in a mixing bowl. Mix thoroughly with a wooden spoon until the mixture turns sticky. Add carrot and chilli to the mixture.
Dust the base of the mushrooms with corn flour, then spoon a heaped tablespoon of filling ingredients and stuff it on the mushroom, patting it into a neat mound. Add a little chopped red chilli. Repeat with remaining filling and mushrooms.
Steam the mushrooms over rapidly boiling water for 1012 minutes.
Remove the mushrooms and place onto a clean plate. Combine seasoning (C) with the reserve stock and bring to a simmering boil. Turn off the flame and add in egg white, then pour the gravy over the mushrooms.