Cook noodles according to package directions; drain and rinse with water. Meanwhile, in a Dutch oven, combine bok choy, pork, broth, soy sauce, ginger and garlic; bring just to a boil. Reduce heat; gently simmer, uncovered, 5-7 minutes or just until bok choy and pork are tender., Add noodles to soup. Serve immediately. If desired, sprinkle with green onions and serve with chili sauce.