In medium saucepan, place carcass, leg, and wing bones with peppercorns, 1/2 tsp salt, large chunks of carrot, halved onion, water, bay leaf, and sprigs of parsley. Place pan on medium heat and bring to gentle simmer. Simmer for about 1 hour, reducing heat as necessary to keep contents at a low simmer. Remove from heat, allow to cool slightly. Strain and discard solids and reserve liquid, which should be about 3 cups.