Bring a large pot of water up to a boil.
Heat oil in a wok or large skillet over high heat. Add ground pork and use a spatula to break it up into tiny bits and allow it to brown and get slightly crisp in parts.
Add Shaoxing wine, 2 tablespoons soy sauce, 5 spice powder, and half of the scallions. Cook for one minute more, then remove from heat and set aside.
Whisk together the remaining 3 tablespoons soy sauce, tahini, black vinegar, sugar, ginger, garlic, and chili oil.
Cook noodles according to package directions, then reserve 1 cup of cooking liquid and use the remaining water to blanch the baby bok choy for about 2 minutes, or until tender but still crisp.
Divide the noodles between 4 bowls (or more if making smaller portions), then add ¼ cup of cooking liquid to each (should still be nearly boiling). Divide pork among the bowls, then pour sauce over top. Let sit for a few minutes, then mix everything together.
Top with chopped peanuts and reserved scallions. Serve immediately.