Save turkey bones, skin, and any pan drippings
Place turkey bones in a large stockpot
Add cold water to cover the bones by 2 to 3 inches
Add onion, carrots, celery, and garlic
Add bay leaves, peppercorns, and fresh herbs if desired
Bring to a gentle boil over medium-high heat
Reduce to a low simmer
Skim off foam and impurities from the surface
Simmer for 2 to 4 hours
Add salt near the end if desired
Strain the broth through a fine mesh sieve
Discard solids
Cool the broth quickly
Refrigerate or freeze for later use