How to Make It
Preheat the oven to 425°. In a small bowl, blend the soy sauce, vinegar, chili sauce and 2 teaspoons of the ginger.
In a large bowl, gently mix the pork with the water chestnuts, scallions, cornstarch, garlic, salt, pepper and the remaining 2 teaspoons of ginger. Fill the mushroom caps with the pork mixture.
In a very large, ovenproof nonstick skillet, heat the oil. Add the shiitake, pork side down, and cook over high heat until browned, 3 minutes. Turn and cook for 1 minute. Transfer the skillet to the oven and bake for 7 minutes, or until the pork is cooked. Serve with the dipping sauce.