Leftover Marinated Steak Sandwiches

I’m not saying you should make extra steak specifically so you can have these sandwiches the next day. But I’m also not saying you shouldn’t.

Because leftover steak is one of those things that can be slightly disappointing the second time around. Reheat it too much and the steak you were very proud of yesterday suddenly has the texture of something you could resole a shoe with.

This is a much better plan.

Slice it thin, pile it into a baguette with tomato and sweet caramelized onions, add a generous swipe of mayonnaise, and give the whole thing just a couple of minutes under the broiler. Long enough to warm everything through and crisp the bread, but not long enough to cook the life out of the steak.

Honestly, there are worse reasons to deliberately make too much dinner.

Ingredients for My Leftover Marinated Steak Sandwiches

This is very much a use-what-you-have sandwich, so I wouldn’t get too precious about exact quantities. The steak is already doing most of the work.

Here’s what I use:

• 1 tablespoon extra virgin olive oil for caramelizing the onion.
• 12 oz (340 g) of cooked leftover steak (the star of the sandwich).
• 1 large onion, thinly sliced, for a sweet, caramelized flavor.
• 1 large ripe tomato, thinly sliced, to add freshness and juiciness.
• Pinch of salt, to help season the onions as they caramelize.
• Mayonnaise, as needed. Or, if you have some of my Cilantro Pepita Dressing in the fridge, use that instead. It gives the whole sandwich a fresher, herby kick that’s really good with steak.
• 2 small, sandwich-sized baguettes. And if you happen to have homemade bread around, this is an excellent place to use it. My Homemade Focaccia Barese makes a very different but very good version of this sandwich: softer, olive-oily, and slightly more substantial.

Makes 2 very generous steak sandwiches. Depending on the size of your baguettes, you could easily cut each one in half and feed four people alongside something else.

How To Make It

I start with the only part that actually requires a little patience: the onion. I heat the olive oil in a nonstick pan, add the sliced onion with a pinch of salt, and cook over medium-low heat for about 30-40 minutes, stirring occasionally, until the onions are soft, golden brown, and properly sweet.

You don’t want vaguely softened onions here. Give them time.

Once the onions are caramelized, I transfer them to a plate. Then I add the thinly sliced leftover steak to the same skillet with 1-2 tablespoons of water, cover, and gently reheat over medium-low heat until the steak reaches 165°F on a meat thermometer. The little bit of moisture helps keep it from drying out.

While the steak reheats, I slice the baguettes lengthwise and place them cut-side up on a baking sheet. I preheat the broiler, then toast the bread for about 1-2 minutes, watching closely so it doesn’t burn.

Once the bread is lightly crisp, I spread mayonnaise over both cut sides.

Then comes the tomato, followed by a generous amount of the warm caramelized onions and finally, the star of the show, the warm steak, sliced nice and thin.

Once everything is piled on, I close the baguettes and press down gently to keep all those delicious fillings in place. Then I cut the sandwiches and serve them straight away, while the steak is still warm and the bread is nice and crisp.

Trust me, this is not a sandwich that improves while you answer three emails.

The Steak Matters, But Not in the Way You Think

You absolutely do not need freshly cooked steak for this. In fact, that rather defeats the point.

What you do want is steak that tasted good the first time around. Whatever marinade or seasoning is already on it becomes part of the sandwich, so this works particularly well with leftover marinated steak that has plenty of flavor of its own.

Cold steak is also much easier to slice thinly, which is exactly what you want here. Thick chunks are harder to bite through and have an annoying tendency to pull half the sandwich out with them.

Thin slices, on the other hand, are easier to bite through and make every mouthful more enjoyable. Just make sure your leftover steak was refrigerated within two hours of cooking and use it within 3-4 days.

Things I’d Happily Add

The original version is deliberately uncomplicated: steak, tomato, onions and mayo. But sandwiches are not really a place where I believe strongly in rules.

• A little Dijon mustard mixed into the mayonnaise is excellent. So is horseradish if you want some heat.
• Arugula adds a peppery bite and a bit of freshness, while a few pickled onions make sense if you don’t have the patience to caramelize an onion that day.
• Cheese is obviously an option. Provolone, cheddar, Gruyère or even blue cheese all work, depending on the steak and how committed you are to needing a nap afterwards.
• And if you have some kind of garlicky, herby or spicy sauce sitting in the fridge, this is exactly the sort of sandwich it was waiting for.

Although if I’m using the Cilantro Pepita Dressing instead of mayo, I’d probably leave the cheese out and add some avocado and arugula instead. At that point it becomes a completely different steak sandwich, which is sort of the beauty of starting with leftovers.