Combine bones, water, and salt and peppers in soup kettle. Bring to a boil, skim, reduce heat, and simmer, partially covered, 2 hours. Remove bones. Cool broth, chill, and skim fat from top. Bring stock to a boil, add bay leaf, thyme, peppercorns, and vegetables; reduce heat, and simmer 1 hour, partially covered. Strain.