San Marzano tomatoes are the most famous plum tomato to come out of Italy. They are grown in the rich volcanic soil at the base of Mount Vesuvius, which gives them a sweet flavor and low acidity and they are coveted for their firm pulp, deep red color, easy to remove skin and low seed count. In fact while regular round tomatoes usually have four or five locules or seed pockets, plum tomatoes like those from San Marzano have only two. THE classic Italian paste tomato with rich, complex, sweet flavor essential for making traditional Napolitano sauces and whole canned tomatoes. The large plants produce loads of small, elongated red tomatoes late in the season and need to be staked. Personally, I like them in salads or just cut up as a snack.