Place shallots in a food processor and pulse until finely chopped.

Transfer to a small bowl.

Working in batches if necessary, place tomatoes in the food processor and pulse until coarsely chopped.

Heat oil in a large, deep skillet over medium heat.

Add shallots and cook, stirring, until softened, 1 to 2 minutes.

Add tomatoes and salt and bring to a boil.

Stir, then cover the skillet and adjust the heat so mixture cooks at an even simmer.

Cook, stirring occasionally, until sauce deepens slightly in color and any large pieces of tomatoes are soft, about 30 minutes.

Uncover and cook until sauce thickens slightly, 25 to 30 minutes more.

Taste sauce; it should taste rich and fresh, but you can add a pinch of sugar, a little more salt or a splash of balsamic vinegar if it needs a kick.

You can also add some ground black pepper or crushed red chile flakes, a minced anchovy or two or fresh or dried herbs, and cook the sauce for a few minutes more.

Make it your own, exactly to your taste.

Store in an airtight container in the refrigerator for up to 1 week or the freezer for up to 6 months.

*Alternatively, you can swap 4 cups canned no-salt-added plum tomatoes with juices (about 1 1/2 [28-ounce] cans) for the fresh tomatoes and reduce the cook time by about 10 minutes.