Restorative Chicken Soup with Ginger

Fill a large pot with 14 cups water, chicken pieces, backbone, wings, parsley, thyme, bay leaf, salt, and peppercorns. Bring to a boil. Skim foam, reduce heat, and gently simmer for 25 minutes. Remove chicken (except wings); continue simmering while you discard skin and remove meat from bones. Cover meat and refrigerate; return bones to pot and simmer 3 1/2 hours more.

Strain broth through a fine-mesh sieve and discard solids, including bones and wings. Skim fat and transfer broth to a clean pot. Add onions, carrots, celery, ginger, mushrooms, and soy sauce. Bring to a boil, reduce heat, and simmer until vegetables are very tender, 25 minutes. In the last 3 minutes of cooking, stir in in the bok choy.

Cut or tear reserved chicken into 3 cups of bite-size pieces. (You'll end up with an extra cup of meat; save it for a salad or a sandwich.) Add to broth, along with cayenne and lemon juice. Heat through, about 2 minutes. Season with salt and pepper; serve.