The recipe is a simple one relying on pot vegetables like onions and celery to enhance a sauce that derives most of its flavor from meat and mushrooms. Some herb, a touch of tomato paste and a final splash of aged sherry vinegar after the sauce has reduced and become syrupy are all it takes.
Heat oil in heavy 4-quart casserole. Brown veal over high heat top and bottom. Remove to platter. Add mushrooms to pot. Sauté, stirring, about 5 minutes, until they start to soften. Add onion, celery and garlic, reduce heat to low and continue cooking, stirring occasionally, until vegetables are soft.
Stir in stock and wine. Return meat to pot, add thyme and pepper to taste, cover and cook over low heat about 1 1/2 hours, until veal is tender when pierced with knife.
Remove veal to platter. Whisk tomato paste into liquid in pot. Increase heat to medium-high and cook about 10 minutes, until liquid in pot has reduced by about half and become somewhat syrupy. Add vinegar, stir, and season sauce to taste with salt and pepper.
Return veal to pot and baste with sauce. Partly cover pot and simmer to reheat about 10 minutes, or set aside and reheat just before serving.