Advocating for a favorite canned tomato is like promoting your choice of vodka (Grey Goose) or jazz pianist (Bill Evans). It's very personal. You may love the puréed Pomi that comes in a small paper container. Or you may trust the food engineers at Cook's Illustrated who seem to love Muir Glen (I think they're too sweet -- the tomatoes, not the engineers). Or perhaps your grandmother always used Red Pack.
For me the only canned tomato to use in my marinara sauce and ragus, in my tomato-based version of Osso Buco (I use Marcella Hazan's recipe from her great The Classic Italian Cookbook), French ragouts and New York pot roasts, is not a brand. It's the San Marzano.
San Marzano tomatoes are grown in the Campania region of Italy, near Naples, where pizza originated so these folks know their tomatoes. The tomatoes are special because they grow in the shadow of Mount Versuvius, famed for destroying Pompeii, in fields that are rich in volcanic soil. The warm sunny weather, stable climate, and proximity to the Mediterranean Sea probably don't hurt, either.
These are plum tomatoes, but thinner and a bit pointier than the ones we see fresh in our local markets, with a nib at the tip. The skin is thick and easy to peel, and when fresh and ripe, the tomatoes are a dark, almost brownish red. I've had the chance to shop vegetable markets in southern Italy and once bought a bag of fresh San Marzanos, turning them into a quick-cooked pasta sauce. Both when eaten raw with a touch of sea salt, or after a few minutes of cooking in a drizzle of locally processed olive oil, their flavor was very close to those that are canned: a strong tomato taste, less sweet yet not too acid, with few seeds and a meatier flesh.
Tomatoes come from nature and that means a change in rainfall or an unpredictably cool summer means one can of tomatoes may not taste like the next. But I've found canned San Marzanos to be consistently excellent with a deep red color, firm flesh and a rich, mellow flavor. They stay longer on the vine than the tomatoes we grow here, and are harvested and canned when perfectly ripe. Most San Marzano brands are canned in juice, not purée, and many, although not all, will contain a sprig of basil (I always discard this). Sometimes the label says salt is added, although I never taste it, and occasionally tasteless citric acid is added to keep the red color bright (salt and citric acid are also added to domestic and other imported tomatoes).
I always buy whole tomatoes, preferring to cut them myself because then I know what I'm getting, instead of someone else's definition of crushed or diced or puréed. Depending on my recipe I just give them a quick cut with a paring knife, or a squish with my hand, or occasionally do a full purée with an emersion blender.
Once a costly and specialty-store item, today San Marzano tomatoes are easy to find in our markets and they don't have to be premium-priced. In New York there are even bargain prices.
All San Marzano tomatoes come from Italy. All are imported. While some plum tomatoes grown here in the U.S. may be delicious and good quality, they are different. San Marzano tomatoes are not just a species -- they are unique to where they are grown and how they are processed.
"San Marzano-style" is not San Marzano. Nor is "Italian style" the same thing as imported from Italy. And just printing the words "pomidori pilati" -- which only means peeled tomatoes -- on the side of a can doesn't make what's inside Italian. Thus you must read each can carefully, including the fine print as to where what's inside the can actually comes from, not just where it was distributed from.
Here's another reason to read the can carefully. There is at least one brand that declares itself San Marzano when in fact, the fine print tells the truth that they are not. One has even branded itself San Marzano -- it comes in a slightly rustic-looking white and green can with red plum tomatoes, each emblazoned with "San Marzano," circling the can -- but these are from California. Besides the deception and their inflated price, the tomatoes themselves are actually not very good, in my opinion.
Back to the real thing. In 1996 the producers of San Marzano tomatoes received the prestigious E.U. "Denominazione d'Origine Protetta" designation which declares a product as superior, similar to France's D.O.C. given to the that country's best wine and food products. That means every can of authentic San Marzano tomatoes will prominently show "D.O.P." on its label.
Excellent brands available in our markets include LaValle, Francesconi, La Bella, Coluccio, Sclafani, Cento, Cirio, and Vanita. If awards are meaningful to you, Food & Wine magazine has named LaValle San Marzanos the best in a taste test.