Boil enough water to blanch the lamb. Once the water is boiled, add the lamb and 4 slices of ginger. Bring to a boil, and cook for 1 more minute. Turn off the heat, and drain and rinse the lamb clean. Set aside.
Heat 2 tablespoons of oil in a wok set over medium heat. Add the remaining ginger, the white parts of the scallions, and the rock sugar. Cook for a couple of minutes before adding in the fermented red bean curd and zhu hou sauce. Stir and let everything cook for a couple minutes, using medium low heat.
Next, turn the heat back up, and add the lamb, stirring to coat the lamb evenly in the sauce. Add in the star anise (if using), the Shaoxing wine, dark soy sauce, light soy sauce, oyster sauce, tangerine peel, Shiitake mushrooms, the mushroom water, and enough additional water to just cover all of the ingredients. Cover and bring to a boil. Then immediately turn down the heat to simmer for 1 hour over medium/low heat. Stir the stew every 20 minutes to prevent sticking.
While the lamb is simmering, prepare the carrots, bamboo shoots, and bean threads. Also, wash the lettuce, shake off any excess water, and place in the bottom of a large serving bowl.
Once the lamb is tender (taste test time!), add in the carrots, bamboo shoots, and bean threads. Cook for another 15-20 minutes over medium heat until the carrots are softened. If you still have too much liquid, cook the stew with the lid off for the last 10 minutes. Salt to taste, stir in the green parts of the scallions, and serve everything on your prepared bed of lettuce.