Simple Tomato Sauce

This sauce is carried by the tomatoes. Everything else is support.

Buy real San Marzanos

Not a suggestion. The recipe is three ingredients and one of them is doing almost all the work, so this is the decision and the rest is procedure.

Look for D.O.P. on the tin. Denominazione di Origine Protetta, which means they were grown in the volcanic soil around Mount Vesuvius and certified, rather than being a tin that says San Marzano because nobody stopped it. The label is the only way to tell, because the name alone is not protected in most places and plenty of tins carry it on tomatoes grown anywhere.

What you get for it: sweeter, markedly less acidic, thinner skins, fewer seeds and much less water. A tin of ordinary plum tomatoes makes a sauce that needs sugar to be palatable and still tastes thin. A tin of real San Marzanos makes a sauce that needs salt and nothing else.

It costs about two dollars more per tin. There is no other two dollars in cooking that buys this much.

Crush them by hand. A blender whips air through them and turns the sauce pale orange. A food processor shreds the seeds and makes it bitter. Squeeze each tomato until it comes apart, keep every drop of the juice, and it takes about a minute.

The other sauce, which takes four minutes

Worth knowing because it needs nothing from a shop.

Butter, pasta water, and cheese. Drain the pasta a minute early and keep a mugful of the water. Butter into a wide pan off the heat, a good splash of the water, and swirl until it emulsifies into something creamy rather than greasy. Pasta in, then grated pecorino or parmesan a handful at a time, tossing constantly, with more water whenever it tightens.

That's cacio e pepe without the pepper, and it's the thing to make when there's no tomato in the house. Pecorino is sharper and saltier; parmesan is rounder and more forgiving. Both work and pecorino is the traditional one.

The water is not optional. The starch in it is what turns butter and cheese into a sauce instead of a lumpy mess, which is exactly what happens if you use plain water or none.

If it's not right

• Acidic or sharp: the tomatoes weren't real San Marzanos. A pinch of sugar is the usual fix and a better tin is the actual one.
• Thin: not reduced enough. Keep going uncovered.
• Bitter: burnt garlic, or the seeds got shredded by a machine.
• Flat: salt. Then taste again, then probably more salt.
• Heavy: the onion browned.