Preheat oven to 425 degrees. Rinse the bones with cold water and pat dry. Place the vegetables in a single layer in a large roasting pan and add the bones on top. Roast, turning the bones a few times, until well browned; about 1 hour.
Transfer the bones and vegetables to a large soup pot, discarding fat from the roasting pan. Deglaze the pan with a couple of cups of water over high heat, scraping up all the brown bits. Add this to the bones, along with the cubed meat, tomato paste, garlic, bay leaves, thyme and parsley. Pour in cold water to cover the bones and bring to a boil. Reduce heat to a simmer and skim off any foam that rises to the surface. Do not stir. Add peppercorns, and continue to simmer, uncovered, for about 4 hours, skimming from time to time.
Strain stock and discard solids. Cool and then refrigerate overnight. The following day, remove and discard fat that has risen to the top, and discard any debris that has sunk to the bottom. Salt before using or, if planning to reduce, wait to add salt until later. Can be stored in the refrigerator for several days, or divided into smaller quantities and frozen for future use, up to 6 months.