1/4 lb. ground pork
1/4 lb. medium shrimp, shelled, deveined and finely chopped
1 scallion, minced
1/4 cup Napa cabbage, finely chopped (green parts only)
2 tbsp. soy sauce
1 tbsp. rice wine
1 tsp. fresh ginger, minced
1 tsp. sugar
1 tsp. sesame oil
1/4 tsp. black pepper
3 water chestnuts, minced
1 tsp. cornstarch
36 medium dried shiitake mushrooms
2 cups water
1 tbsp. chicken base
4 tbsp. mushroom soaking liquid
3 tbsp. oyster sauce
1 tbsp. cornstarch + 1 tbsp. mushroom soaking liquid (cornstarch slurry)
1. Place dried shiitakes in a large bowl and cover with very hot water. Let soak for about 30 minutes until softened. Remove mushrooms to a chopping board and reserve the mushroom soaking liquid.
2. Cut the stems off the reconstituted mushrooms and discard. Set aside the caps.
3. For the filling, mix together the ground pork, chopped shrimp, minced scallion, chopped napa cabbage, 2 tbsp. soy sauce, 1 tbsp. rice wine, 1 tsp. minced fresh ginger, 1 tsp. sugar, 1 tsp. sesame oil, 1/4 tsp. black pepper, minced water chestnuts, and 1 tsp. of cornstarch in a large bowl.
4. Fill each mushroom cap with about 1 heaping teaspoon of the filling, then top with a fresh cilantro leaf. Place filled mushroom caps on a foil-lined baking sheet and set aside.
5. Mix together 2 cups of water, 1 tbsp. of chicken base (or you can substitute with 2 cups of low sodium canned chicken broth) and 4 tbsp. of the reserved mushroom soaking liquid. Pour 1 cup of this mixture into a bowl and stir in 3 tbsp. of oyster sauce. Set aside.
6. In a small bowl, stir together 1 tbsp. of cornstarch and 1 tbsp. of the mushroom soaking liquid and set aside.
7. Heat 1 tbsp. of vegetable oil in a large saute pan or wok over medium high heat. Add the mushrooms, filling side up, in a single layer (if too crowded, cook in two batches). Reduce heat to medium then cook the mushrooms for several minutes or until they just start to brown. Add the 1 cup of reserved mushroom soaking liquid and oyster sauce, bring to a boil, cover, reduce heat and simmer until the meat filling is cooked through.
8. Remove mushrooms to a serving platter. Add the remaining 1 cup of the chicken stock mixture to the pan, bring to a boil, then add the cornstarch slurry. Cook until the sauce has thickened (1-2 minutes).
9. Pour the sauce over the mushrooms and serve immediately.