Diced tomatoes promise neatness and convenience: There are no juice-filled water balloons to crush or snip or coax into softness, slowly and patiently, on the stove.
But here's an ironic surprise: Diced tomatoes—which you'd expect to break down much faster (since, duh, they're smaller)—are actually packaged to keep their shape. Those diced tomatoes you bought to save time are making achieving a smooth, homogenous sauce harder (and slower). Those liars.
Food science expert (and whole canned tomato evangelist) J. Kenji López-Alt doesn't call for diced canned tomatoes in his book The Food Lab because...
Chopped tomatoes have lots of calcium chloride to help them keep shape. They don't break down properly as a result. Always use whole canned! https://t.co/DsKAC44Ar9
Diced canned tomatoes are good if you're making a slow-cooked dish but you still want distinct tomato pieces—maybe in chili, stew, braises, or, depending on your preferences, shakshuka.
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But whole or crushed canned tomatoes are likely the better choice for any sauces, soups, or baked pastas where the tomatoes should melt down completely.
If you do find canned diced or chopped tomatoes (like Pomì) that don't list calcium chloride as an ingredient, however, you can use them as you would their whole brethren without worrying that they'll retain their cube-like shape no matter how long they're simmered.
As for avoiding the mess of crushing tomatoes (which, if you're wearing an apron, can be a satisfying tactile experience), we've got some recommendations below; Kenji pokes a hole in every tomato before he squeezes out to direct the spray of juice.
While canned tomatoes sure are handy—and we on the East Coast are pulling our reserves from pantries (and bookshelves and bedroom closets)—, let me offer just a brief reminder of the fresh (!) summer tomatoes we can look forward to...
A (former) student of English, a lover of raisins, a user of comma splices. My spirit animal is an eggplant. I'm probably the person who picked all of the cookie dough out of the cookie dough ice cream. For that, I'm sorry.