How to Make It
Place the carcass and skin of roasted turkey in a very large stockpot. Add chicken broth, water, chopped celery, chopped carrots, onion, and salt. Bring to a boil over high; reduce heat, and simmer until carcass falls apart and stock tastes very rich, 2 to 3 hours. Remove and discard large bones; pour liquid through a fine wire-mesh strainer, and discard solids. Cool completely, about 2 hours; cover and chill until ready to use. Skim and discard solidified fat before using. Refrigerate stock up to 1 week, or freeze up to 6 months.