Spanish Salsa Verde Turns Leftover Steak Into a Fantastic Salad

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Leftover steaks make a great cold supper. [Photographs: J. Kenji López-Alt]

I love leftovers. And not just in the I love picking at cold pizza the morning after a long night of drinking kind of way that everyone loves leftovers, but in the oh joy, I get to figure out a fun and exciting way to use up this junk in my fridge and pass it off as food I was planning on making all along kind of way. Restaurant chefs play this game all the time, transforming last night's leftovers into today's special.

Lucky for me, as someone who tests and develops recipes for a living, I have a lot of leftovers all the time, which means that I get to play this game any time I have a dinner party.

For several weeks, I was testing out a recipe for lomo al trapo, a Colombian dish of beef tenderloin crusted in salt and cooked directly on a pile of hot embers. That means that for several weeks, I served cold leftover steak, prepared in a variety of ways, at dinner parties.

People often ask me what the best way to reheat steak is. My advice? Don't. Nothing beats a cold steak salad for an easy, hearty appetizer or light meal.

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Though I served that leftover steak in many forms, nearly all of them ended up revolving around salsa verde. I'm not talking the Mexican kind made with tomatillos and chilies—I'm talking the Spanish version of the sauce, made with pickles, capers, anchovies, fresh herbs, and lots of olive oil. It's one of my favorite sauces in the world, and it goes remarkably well with cold meat.

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It's also a dream come true for a condiment- and pickle-hoarder like me. If you've ever looked at your pickle shelf and thought to yourself, "I wonder what would happen if I chopped all of these up and stuck them together," here's your answer: deliciousness. If you balance it, that is. My salsa verde evolved from the version I used to make when I was a cook at Toro, a Spanish restaurant with locations in Boston and New York. Aside from the capers, pickles, and anchovies, I also toss in some finely minced shallots, garlic, and a small spoonful of Dijon mustard (it's not traditional, but it works). The herbs used in salsa verde can vary by region and personal taste, but for this particular version, I found that parsley and mint proved the best counterparts for the meaty steak and sweet corn that I tossed them with.

A splash of sherry vinegar adds yet more bright acidity, which is then counterbalanced by a whole mess of extra-virgin olive oil—enough that the emulsion just starts to break. This isn't the kind of dressing you're going to toss a green salad with, so don't worry if it looks a little oily for now. The steak and corn can take it.

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As for the corn, I happened to have some excess grilled corn lying around that was perfect for this application, though plain old steamed or microwaved corn would be quite tasty as well. To finish the dish, I tossed the sliced steak, the corn (cut from the cob), and a thinly sliced red onion with a good amount of the salsa verde, then transferred it to a serving platter and spooned more salsa on top.

If you want to be all civilized here, you could hand out small plates and forks for your guests to help themselves. But with food this delicious, I prefer to keep things a little more primal: I just pass out forks and let everyone dig in off the communal platter.

The real question then becomes: What happens when I have leftovers of the steak salad that I made with leftover steak? At this stage, though, the question is purely academic, as I have never seen leftovers of this dish.