Marcella Hazan’s classic tomato sauce is so good and right and simple that describing it feels superfluous. The recipe comprises just three ingredients: a can of tomatoes, five tablespoons of butter, and a peeled onion, cut in half and simmered in the sauce. Plus salt, of course. (If that counts as an ingredient, I suppose there are four.) The genius of Hazan’s sauce lies in the fact that, although it’s basically a convenience food, made of only inexpensive, shelf-stable ingredients, it can’t be improved upon. Add fancy olive oil or fresh Genovese basil if you’re moved to; they won’t make it any better. The sauce is already as good as can be.
There’s nothing original in my high estimation of Hazan’s sauce. If you look her recipe up online, you’ll find yourself in a mise en abyme of admiration. I’m adding to the already sizable œuvre of sauce commentary only to address an often overlooked detail: What are you supposed to do with the onion once the sauce is done? The butter and salt dissolve, melting together with the tomatoes and cohering into sauce. The sauce goes on to anoint spaghetti, get simmered with eggs for shakshuka, top pizza, and so on. The onion, though, gets plucked out of the sauce and discarded. It’s a remainder, an odd bit, a cracked eggshell, absent-mindedly swept into the garbage.
It’s understandable that this issue hasn’t been widely dealt with. Hazan’s sauce is already too good to be true. Why be so bold as to ask for something more? I appreciate the collective grace of not worrying about the onion. But it’s a great onion! With the same ingredients, combined in a different ratio, it could just as well be the final product of your cooking as the refuse. The onion, after all, has been simmered in sweet acid and a lot of butter. Recipes that celebrate this exact union—of long-cooked onion, fat, and tomato—proliferate. Think of the South Indian soup vengaya rasam, tarte Provençal, and more recent variants on pasta all’amatriciana. All are united by a reliance on the same old and unimprovable formula that defines Hazan’s sauce.
Once you reconceive of the simmered onion as something that could have been intentionally produced, you begin to see its possibilities. The sweet, lightly acidic, tomatoey, buttery Hazan onion could be used, with a little coaxing, in any of the dishes I mentioned above. I haven’t tried them all because I have two reliable uses for my onions, and I like them so much that I haven’t found reason to stray.
The first is to make the onion a fast, if unconventional, replacement for the fresh tomato and scallion or chive in fān qié chǎo dàn, or, roughly, Chinese tomato-and-egg stir-fry. If I have fresh tomatoes, I follow any of a number of traditional recipes for the dish, which call for cooking the eggs first in oil, then scooping them out of the pan, cooking tomatoes down in the same oil, adding the eggs back in, and finishing with salt and scallions or chives. If I don’t have fresh tomatoes, or if I do have a Hazan onion, I chop it messily with all its tomatoey juices and do basically the same thing: cook eggs in oil, scoop them out, then add the onion and juices to the pan. I sometimes add chopped ginger, per a recipe by Francis Lam, and a sprinkle of Shaoxing wine. Then, when the mixture is a little soupy, I add the cooked egg back in and serve it over rice. (Lam’s version has some ketchup, too.)
Second: Think of how delicious hardy cooking greens (such as kale or rapini or broccoli rabe) are when they’re just lightly sweetened and enriched with sun-thickened tomato passata. First, you would have softened garlic or onion with salt in olive oil, then added the tomato and greens, letting them darken and wilt into a savory slump. To make a version of the same dish, I slice the Hazan onion into soft slivers, heat a pan, add olive oil, then don’t bother with garlic—or maybe do. Then I add the onion and kale together with, if it’s summer, some extra cherry tomatoes, which will burst pleasantly, and let it all cook until any distinction among the ingredients has disappeared. You might be in Greece or Sicily. Or in your apartment as summer sets in, your vacation plans scuttled, with nothing planned now except to make a pot of Hazan’s sauce and use up every last ingredient.
