When people talk about San Marzano tomatoes, they may mean one of two things. First, says Karl S, there is an area near Naples (a DOP, or Denominazione di Origine Protetta) famed for its volcanic soil and quality of its tomatoes. Only cans marked DOP hold tomatoes grown in this region, and as supplies are limited, such tomatoes are more expensive.
The second possible meaning for San Marzano is a variety of plum tomato similar to those grown in the DOP near Naples—but not actually grown there. This is not to say that San Marzano–variety tomatoes grown in your area are inferior to those grown and canned in Italy. In fact, since you may be able to obtain them fresh, local tomatoes may be even better in terms of taste. And for canned tomatoes, factors other than geographic origin influence flavor, such as whether the can is lined with enamel.
Of the tomatoes from San Marzano DOP proper, Porthos particularly recommends the Strianese brand. They’re much sweeter and more vibrant-tasting than other DOP San Marzano canned tomatoes—and harder to find. “If you do find some, taste them right when you open the can (careful or you’ll eat the whole thing),” says Porthos.
Board Link: San Marzano Tomatoes