Easily transform leftover steak into flavorful hot sandwiches you’ll be craving with just a handful of kitchen staples. Steak, horseradish aioli, sharp cheddar, and grilled onions pile onto crusty bread for a delicious and different way to use up leftovers.
It’s incredibly rare that I deem something “the best” on here. Out of nearly 500 recipes on this website, only three have “best” in the title.
But this leftover steak sandwich recipe is well worthy of the descriptor! In fact, I look forward to eating it just as much as the freshly-grilled steak in the first place.
Why This Recipe Works
- Leftover steak is generally not-as-great when reheated the next day and risks turning tough and dry. By chopping the steak small and browning it on a griddle pan, you get pieces that are easy to eat and not chewy in the slightest.
- This sandwich recipe is straight-forward and quick, but tastes “fancier” than the effort involved.
- By turning a piece of leftover steak into a sandwich with horseradish aioli, sharp cheddar, and grilled onions means you get an entirely different meal – no boring leftovers.
- Aioli: While a store-bought variety will certainly work, horseradish aioli is really easy to make at home. This homemade kind uses shortcuts and starts with mayonnaise and can be made with either prepared or cream-style jarred horseradish.
- Onion: Slicing half of an onion (instead of dicing it) helps the pieces stay together in the sandwich filling and makes less of a mess when you’re eating it.
- Cheese: Your favorite cheese that meshes with these flavors will work here, but I’m partial to an extra-sharp white cheddar.
- Bread: Same for the bread. Use your preferred bread. Ideally I cut slices from a crusty loaf of Italian or French bread, but I’ve totally used regular sandwich bread before and that was just fine.
- Steak: Many types of cooked steak will work here! The ingredients of this leftover steak sandwich can be scaled up to make more than two servings. Each sandwich uses just over two ounces of cooked steak.
There is a fair amount of leeway here as for what kind of steak to use as this recipe takes into account using leftover cooked steak, and not cooking it specifically for this sandwich.
We most often make ribeyes, so that cut is often what I use here. It could lean pricey buying ribeye specifically to make sandwiches (versus enjoying it prepared on the grill), but only 4-5 ounces of cooked steak is required to make two nicely-sized sandwiches. The amount used can vary, but that’s usually the amount the two of us have leftover after cooking two steaks for dinner the night before.
That said, I have personal experience using leftover portions of NY strip and flat iron steaks and they’ve been great, too.
- Slice half of an onion. To do this easily, slice an onion in half and set aside the other half for other purposes. Slice off the top stem area, then slice a “V” notch down through the root end to remove that. Lay the onion half flat on the cutting board and cut thin vertical slices.
- Next cut the steak into small pieces. If there are excess fatty areas you can remove them at this time if you like.
- Place a large skillet or a flat griddle pan on the stove over medium heat and add a teaspoon of oil. Once heated, add the sliced onion and cook for 4-5 minutes, or until golden to golden-brown.
- Slide the sautéed onion to the side of the pan (or temporarily remove it to a separate plate if you don’t have enough room), add the remaining teaspoon of oil to the pan, and raise the heat to medium-high. Add the steak and cook for 3-4 minutes, or until the meat is well-heated throughout and has browned.
- Slide the onions back over (or add them back to the pan) and stir them up with the steak. Add sliced cheese to the top of the mixture.
- Cook until the cheese has melted, then fold the melted cheese into steak and onions. Dispersing the melted cheese throughout also helps hold the filling together, making for a less messy sandwich.
- Spread horseradish aioli onto four slices of bread, then add the steak/onion/cheese mixture to two of them.
- Cook the sandwiches in the pan in your preferred manner, until both sides are golden-brown and have crisped. Cut in half and serve warm.
- Cut the steak into fairly small pieces. This way you don’t have to chew through chunks when eating it, making a mess in the process (if you’re anything like me!).
- You can make the aioli up to a couple of days ahead of time to streamline the sandwich assembly process. Start small with the horseradish (prepared or cream-style), take a taste, then add more as you see fit. Same goes for the other ingredients.
- This leftover steak sandwich would also do well cooked in a sandwich/panini press.
For this sandwich cooked ribeye, NY strip, and flat iron steaks all work very well. Other cuts will likely work, like chuck eye, sirloin, or porterhouse steak, as you’ll need between four and five ounces for this leftover steak sandwich recipe (which makes two servings).
A side salad with heft, such as a kale caesar salad with Greek yogurt caesar dressing or hummus salad dressing is a great pairing. As assortment of vegetables, such as roasted broccolini, roasted frozen broccoli, or garlic sauteed green beans also would work with these flavors.
If you’ve enjoyed this recipe, I’d love for you to leave a star rating in the recipe card and/or a comment review below!
The Best Leftover Steak Sandwich
- 3 Tablespoons horseradish aioli
- Half of a medium onion thinly sliced
- 4.5 ounce cooked steak
- 2 teaspoons olive oil, divided
- 1.5 ounce cheese such as extra-sharp cheddar
- 4 slices crusty bread
- Butter for cooking sandwiches
- Prepare the horseradish aioli. This can be done up to a few days ahead of time, as the flavors meld well in the refrigerator.
- Spread one side of four slices of bread with about 2 – 2 ½ teaspoons of horseradish aioli each (using 3 Tablespoons in total). Set aside for now.
- Slice half of a large onion into thin slices. Slice cooked steak (can be cold from the refrigerator) into thin strips, then slice the strips perpendicularly so that the steak is in small pieces. Discard any fatty bits as you see fit.
- Heat a griddle pan or large skillet on the stove over medium heat. Add one teaspoon of oil to the pan and once heated, add the sliced onion. Cook for 4-5 minutes or until the onion turns golden-brown, flipping/stirring up the onion frequently so it doesn't burn.
- Once the onions are golden-brown, remove them to a separate plate for the moment (or slide them to the slide of the pan). Add another one teaspoon of oil to the pan and raise heat to medium-high. Add the sliced pieces of cooked steak and cook for 3-4 minutes to heat and brown them nicely.
- Add the onions back to the pan (or slide them back over) and stir everything to mix up the steak and onion evenly. Add sliced cheese in a single layer on top of the steak/onion and cook briefly until the cheese has melted, then fold the cheese into the mixture.
- Divide the steak/onion/cheese mixture evenly between two slices of bread, placing it on the aioli-covered side. Cap off each sandwich with the remaining two slices of bread, aioli-side down.
- Add a small amount of butter to the pan and place it on the stove over medium-low heat. Once melted, place both sandwiches in the pan and cook until golden to golden-brown on the bottom. Add another small bit of butter to the pan, flip sandwiches over, and cook until the other side is golden-brown (or done to your liking). Slice sandwiches in half and serve right away.
- Cutting the steak into fairly small pieces makes this leftover steak sandwich easily to eat. You won’t have to bite through a bigger hunk of steak in the middle of the sandwich and it keeps the filling from spilling out.
- Instead of using butter to cook the sandwiches, mayonnaise makes a nice option, too. Simply spread a thin layer of mayonnaise on one outer side of the sandwiches, then place the mayo-side down in the heated pan (no oil or butter needed). Right when you place the sandwiches down spread mayonnaise on the other, top side of bread. Cook and flip until golden-brown on both sides.
Nutritional information is provided as an estimate. As it can vary due to many factors (brands used, quantities, etc.), we cannot guarantee its accuracy.