Tie the knuckle of veal and season with salt and pepper. Brown in an ovenproof dish. Add the chopped onions, carrots, garlic and herbs and leave to sweat. Try to prevent the onion from burning. Pour over the white wine and reduce. Add 2 liters veal stock. Cover and bake in the oven at 80ºC / 175ºF for 7 or 8 hours, checking that the liquid does not evaporate. Remove when the meat is tender.
Cut the leg of veal into pieces and brown in the oven. Reduce 1 l / 4 1/2 cup/ 1 3/4 pt veal stock with the leg of veal. Flavor with thyme. The reduction should end up very thick so that it can be used to glaze the meat. Remove the knuckle meat from its cooking juices, dry and brown in oil and butter. Place in the oven at 220ºC / 425ºF to give it a better color and a crisper texture. Remove the string. Glaze with the reduced veal stock and return to the oven. Repeat this operation until the veal is well glazed all over. Strain the cooking juices, reduce to the desired consistency, bind with a little butter and season with salt and pepper.