Preheat oven to 350 degrees Fahrenheit.

Coarsely chop garlic, rosemary, thyme, salt and pepper in a food processor. Set aside one tablespoon of this mixture. Press remainder into center of veal through openings of string at either end. Coat the outside of the roast with porcini mushroom powder.

Heat oil in heavy large pot over medium heat. Add bones and brown well, about eight minutes. Transfer bones to bowl. Add veal to pot and brown on all sides, about five minutes. Add reserved one tablespoon of the garlic mixture and remaining mushroom powder to pot, around the veal. Arrange bones around the veal.

Add chicken stock, wine, tomato paste and vinegar. Bring to boil. Cover, place in oven, and roast until veal is tender, about two hours. Uncover and cool veal for an additional one hour. Discard bones and refrigerate until cold.

Transfer veal to cutting board, scraping any sauce back into the pot. Remove strings. Slice veal into half-inch-thick slices. Place slices in large oven-to-tableware baking dish, overlapping to fit.

Pour sauce into a saucepan and boil until reduced to approximately three cups, about 20 minutes. Season to taste with salt and pepper and spoon over veal.

To reheat, place roast, uncovered, for 25 to 30 minutes in an oven heated to 350 degrees Fahrenheit.