To make veal stock:
Preheat the oven to 450 degrees F.
Remove meat from bones where possible and cut into 1-inch pieces. If using breast bones, cut apart. In roasting pan, arrange bones and meat in 1 layer, drizzle
with oil, season with salt, and pepper and roast
in lower part of the oven, stirring half way in between until bones are golden brown, 40 minutes to 1 hour depending on the size of the bones. Add the tomato paste
by spooning it over the bones. Add the vegetables and put it in the oven for an additional hour.
Into a large stockpot, add bones, meat, roasted vegetables, herbs
, and 16 cups (4 L) water. Discard fat from roasting pan. Place tray back onto the stovetop. Heat on medium for about 1 minute then remove. Immediately add 1/2 cup to 1 cup water to the pan, scraping up brown bits, put the tray back on heat and then add the deglazed liquid to the stockpot. Bring liquid to a tremble, about 190 degrees F, and cook at 190 degrees F (skim froth frequently during first hour of cooking) for 8 hours.
Pour stock in batches through a large fine sieve
and discard solids. Skim
off fat. (Alternatively, cool stock, uncovered, and chill, covered. Scrape congealed fat from chilled stock.) Gently simmer stock, skimming froth occasionally, until reduced to about 4 cups (1 L), about 1 hour. Cool stock, uncovered, and chill, covered. Stock keeps, covered and chilled, 1 week or, frozen in airtight containers, 3 months. If desired, pour cooled stock into ice-cube trays with 1-ounce cups and freeze. Frozen cubes keep in heavy-duty sealable plastic bags 3 months.