For the tomato sauce, heat the oil in a pan with the garlic. When you can smell the garlic, add the tomatoes and 1 teaspoon of salt. Mash up a little with a wooden spoon and simmer for about 15 minutes, or until the tomatoes and oil have melted into each other. Add the basil leaves and simmer for another couple of minutes.
Meanwhile, put the veal slices flat on a board. Lay a piece of ham on top of each one, then a slice of mozzarella over the ham. Scatter a teaspoon of parmesan over each one and roll up securely. Stitch them closed with toothpicks, so that the toothpicks lie flat and don’t stick up. Don’t worry if they all look different. Put the flour on a plate and lightly roll the involtini in it to coat them on all sides. Shake off the excess flour.
Heat the oil in a large frying pan and fry the involtini for just a few minutes, turning them often so that they are golden brown all over. Scatter them with a little salt when they are done, remembering that the tomato sauce is well salted. Leave them in the pan and add the tomato sauce, making sure they are coated. Cover with a lid and simmer for a minute or so. The mozzarella will have softened and started to melt. Remove from the heat but leave the lid on for a minute longer to cook the meat all the way through. Serve immediately, whole or sliced up, with extra toothpicks to use as forks.