If possible, buy thin slices of veal cut from one muscle. If not possible, then buy veal chops and remove the meat from the bones. Pound veal to ⅛-inch thickness (step 3).
Peel onions. Cut down in thin wedges. Sauté in skillet with 2tablespoons olive oil. Cover and cook about ½ hour. Put tomatoes into another skillet with remainder of olive oil. Cook tomatoes about 20 minutes and then pour into strainer and let juices drain out.
Put drained tomatoes and garlic into skillet with a chunk of butter. Bring to a boil and then simmer while veal is cooking.
Coat pounded veal slices with flour. Heat chunk of butter in skillet. Add veal slices. Sauté each side about 5 minutes.
Put veal down the middle of a hot serving platter. Add Madeira, white wine, and stock to skillet. Boil to reduce the liquid to half. Season with salt and pepper. Taste and adjust seasonings.
Put a tablespoon of tomatoes on every other end of each veal steak, and put a tablespoon of onions on the alternating ends. Strain pan liquid down the middle and decorate each steak with a slice of lemon sprinkled with minced parsley.