Remove any large, thick stems from the spinach and rinse the leaves in cold water. Put the spinach in a pot with just the water that clings to the leaves and sprinkle with salt. Cover and cook over medium-high heat until all the spinach is wilted. Drain in a colander and press with a large spoon to remove as much water as possible.

Lay the veal flat and trim the excess fat (do not remove all of it, or the roast will be too dry when done). Spread the spinach over the veal and add the garlic cloves evenly spaced apart. Roll up the veal jelly-roll fashion and tie it securely with kitchen twine.

Put the butter and vegetable oil in a heavy braising pan that will hold the veal comfortably and place it over high heat. When the oil and butter are hot, put in the veal and brown it well on all sides. Season with salt and pepper, then add the wine. Allow the wine to bubble for 1 to 2 minutes to evaporate the alcohol and use a wooden spoon to loosen the tasty bits stuck to the bottom of the pan. Add the tomatoes. When they begin to bubble, lower the heat so that the contents of the pan cook at a gentle but steady simmer. Cover the pan with the lid slightly askew and cook until the meat is tender when pierced with a fork, about 1 1/2 to 2 hours. Turn the meat from time to time and add a little water to the pan if all the liquid evaporates before the veal is done.

When ready to serve, cut the veal in slices about 1/2 inch thick and remove the twine. If the sauce in the pan needs to be reduced, raise the heat and cook until it is thick enough to coat a spoon. Arrange the veal slices on a platter and pour the hot sauce over them. Serve at once.

Note: The veal can be prepared and cooked a day or two ahead of time. When you are ready to serve, slice it and reheat the slices in the sauce over low heat.