1Preheat the oven to 375°F (190°C). In a Dutch oven or other heavy, lidded ovenproof pot, combine the veal, wine, stock, leek, carrot, onion, celery, thyme, bay leaf, garlic, and salt. Place over medium-high heat and bring to a boil, stirring occasionally. When you have a nice boil going, cover the pot and transfer it to the oven. Bake for 2 hours.
2Remove the pot from the oven and then carefully proceed to remove and discard the vegetables and aromatics. (If you want to hold onto the carrots, you can always purée them along with potatoes to make a nice mash.) With a slotted spoon, remove the veal pieces and place them on a tray or plate close by.
3Put the pot with the remaining liquid back on the stove top over medium heat. Stir in the cream and mustard and reduce, stirring occasionally, for 15 minutes, or until the sauce coats the back of a spoon.