Trim bok choy and separate dark green tops from white stems; leave tops whole and thinly slice stems. Peel ginger and finely chop half of it. Slice remaining ginger into thin matchsticks.
Bring a large pot of salted water to a boil. Add noodles and cook according to package instructions. Drain and run under cool water; drain again.
Heat 1 tablespoon peanut oil in a large skillet over medium-high heat. Add pork and cook, breaking up with a fork, until golden and cooked through, about 10 minutes. Season with salt, 1 1/2 tablespoons soy sauce and 1/2 tablespoon rice wine vinegar. Use a slotted spoon to transfer meat to a bowl.
Add remaining 1 tablespoon oil to skillet. Stir in half the scallions, the finely chopped ginger, the garlic and the chile. Cook until fragrant, about 1 minute. Add bok choy stems and a pinch of salt. Cook until bok choy is almost tender, about 2 minutes. Toss in leaves and return pork to skillet.
Toss noodles, remaining 1/4 cup soy sauce and 1 1/2 tablespoons rice vinegar into the pan. Cook until just warmed through.
Transfer to a large bowl and toss with remaining scallions, sesame seeds, sesame oil and herbs. In a small bowl, combine ginger matchsticks with just enough black vinegar to cover. Serve ginger mixture alongside noodles as a garnish.
The New York Times