If you can't find dried shiitake mushrooms, feel free to use fresh, but be sure to saute them first. You can use rice wine instead of sherry, if you like.
A few tablespoons of a cornstarch slurry can be stirred in at the end for a thicker "sauce." Just mix 2 tablespoons water with 1 tablespoon cornstarch.
You can also brown the meatballs in a 475-degree (245 degrees C) oven, instead of broiling.
To make your own hot chili oil for garnish, crush 1 teaspoon red pepper flakes with vegetable oil in a mortar and pestle and let sit for 3 hours to overnight.
This can be served as-is, or with noodles added to the bowl.