Which brings us to the QUALITY of a tomato. The San Marzano tomato is considered the best cooking tomato available. This variety has been grown since the middle ages, and has firm flesh, few seeds and a delicate skin. To this day, they are still harvested by hand, which is part of what drives their cost up.
I've been buying San Marzano tomatoes for 25 years, and can attest to the marked contrast between supermarket brands and the real deal from Italy. There are slight variations among brands, but any real San Marzano should have a great taste.
Authentic San Marzano's will be labelled D.O.P. (Denominazione d' Origine Protetta), indication of their registered status by the EU.
In order of preference, here's how I rank canned tomatoes. They will be labelled "whole plum tomatoes" or "peeled plum tomotoes" or "pomodoro pelati" and may often contain a leaf or two of basil. Crushed tomatoes are also useful for some dishes. Chopped, diced, strained, and otherwise mutilated tomatos are, in my mind, well, mutilated.
- Authentic San Marzano tomato imported from Italy
- Other plum tomatoes imported from Italy
- "San Marzano Style" tomatoes, usually domestic
- Organic or premium brands, such as Muir Glen
- National and store brand whole or mutilated tomato
To make things confusing, one commonly distributed brand is called San Marzano. But that's just the brand name, they are not actually San Marzano tomatos. They are plum tomatos, and they are imported from Italy, but they're not quite as good as the real thing.