You can make this in under 30 minutes. I've used leftover rotisserie chicken and cut even more time off. Note: Keep the bok choy greens and stalks separate after they've been prepped because they are added to the soup at different times. To make the minutes count: while the chicken browns, prep the onion. While the onion browns, prep the bok choy.
Heat the broth mixture: Bring broth, ginger, garlic, sherry, and soy sauce to boil, covered, in large saucepan and set aside. Season and brown chicken: Meanwhile, pat chicken dry with paper towels, then season with salt and pepper. Heat oil in large Dutch oven over Med-High heat until lightly browned, about 5 minutes. Add broth mixture and cook: turn heat to LOW and strain broth into Dutch oven, scraping up any browned bits. Add bok choy stalks and browned chicken. Cook, covered, until chicken is cooked through and no longer pink in center, about 10 minutes. Remove chicken and add noodles: Remove chicken from the pot and stir in noodles. Increase heat to MED-HIGH and cook until noodles are just tender, about 3 min. Shred chicken and finish: While noodles are cooking, shred chicken into bite-sized pieces. Stir in bok choy greens and cook until just wilted, about 1 minute. Turn off heat, stir in shredded chicken and scallions. Season with salt and pepper to taste and serve.