This Steak Sandwich with Grilled Onions is restaurant-level goodness piled high on ciabatta bread with a tangy mustard-mayo sauce. And, believe it or not, it’s ready in just 30 minutes!
Few things are as satisfying as sinking your teeth into a sandwich that’s full of tender slices of juicy steak and sweet, caramelized onions. This steak sandwich hits all the right notes with the kick of tangy mustard mayo and the peppery bite of arugula. It’s a sandwich you won’t forget anytime soon.
This recipe is inspired by a classic, and over the years, I’ve made my own changes and refinements to create a sandwich that’s completely irresistible. It’s simple yet indulgent and requires minimal prep. That’s a win-win for any busy cook!
The real magic comes from the caramelized onions, which add their rich, slightly sweet flavor to complement the savory steak. Then I top it with a handful of arugula and a slather of mustard mayo, and it’s a sandwich that’s a meal on its own.
— This post was originally published on March 9, 2009. It has been updated with new photos and additional information.
Recipe Snapshot
Cuisine: American
Cooking Method: Stovetop
Total Time: 30 Minutes
Servings: 2
Primary Ingredient(s): Strip steak, onions, ciabatta rolls, baby arugula, mayonnaise, mustard
Skill Level: Easy
Ingredient Notes
This post contains affiliate links. Lana’s Cooking is reader-supported and earns a tiny commission at no extra cost to you when you shop from our links.
- New York strip steak — This cut gives the sandwich a juicy, rich texture. If you prefer a more moist, fattier beef, feel free to use ribeye.
- Yellow onions — My choice for caramelization because of their natural sweetness.
- Fresh thyme — A little fresh herb, such as thyme, adds a subtle extra flavor to the onions.
- Ciabatta bread — I like to use the smaller ciabatta buns (or rolls) for this recipe. You could also choose a baguette or an Italian loaf. Just make sure it’s a sturdy, chewy bread hearty enough to stand up to the steak and all the toppings.
- Baby arugula — The peppery taste of arugula makes a nice contrast with the richness of the steak and onions.
- Dijon mustard — Adds a sharp tang to the mustard mayo, which cuts right through the richness.
- Whole-grain mustard — I use this in addition to the Dijon for a little more texture and mustard depth to the sauce.
- Mayonnaise — Adds creamy smoothness to the sauce.
The complete ingredient list with detailed measurements is included in the printable recipe card at the bottom of this post.
How to Make Steak Sandwich with Grilled Onions
Make the Mustard Mayo Sauce
- Stir all ingredients for the sauce together in a small bowl and set it aside until needed.
Prep and Cook the Steak
- Season the steak liberally with salt and pepper on both sides.
Pro Tip
You’ll have the best results if you start with a steak that’s at room temperature.
- Heat the olive oil in a medium skillet over high heat until it’s almost smoking.
- Add the seasoned steak to the hot pan and sear on each side for about a minute.
Pro Tip
The pan should be very hot for this step. I use a cast iron skillet because it gets really hot and holds the heat for a long time.
- Reduce the heat to low and cook the steak for about 7 to 10 minutes for rare, and up to 15 minutes for well done.
- When the cooking time is finished, remove it to a plate and cover tightly with aluminum foil. Allow the steak to rest for 10 minutes while you cook the onions.
Make the Caramelized Onions
- Using the same pan without cleaning it, heat 1 1/2 tablespoons of olive oil over medium heat.
- Add the onions and thyme and saute, stirring often, for about 10 minutes or until the onions are brown and caramelized.
Pro Tip
Stir the onions often, making sure you turn them over frequently so they all cook evenly and turn a golden, caramel brown.
Assemble the Sandwiches
- Slice the steak on an angle across the grain.
- Spread the mustard-mayo sauce on top and bottom of the bread.
- Place a layer of steak strips on the bottom of the bun, sprinkle with salt and pepper, and top with the caramelized onions.
- Place baby arugula on top of the onions and cover the sandwich with the top half of the bun.
Recipe Success Tips
- To prevent the steak from being tough, make sure to slice across the grain and don’t overcook it—medium rare to medium is perfect for this sandwich. Of course, if you really enjoy your steak well done, then that’s the way you should cook it!
- If the onions seem to be getting too brown too quickly, lower the heat slightly and add a splash of water to prevent burning.
- If you think the bread is a bit too soft, toast it lightly for a little extra crunch before assembling the sandwich.
Recipe Variations to Try
- Add melted provolone, Swiss, or blue cheese.
- Swap the arugula for spinach or mixed greens with a milder flavor.
- Add a teaspoon of minced garlic to the onions near the end of cooking.
- Add a tablespoon of butter to the pan with the steak near the end of the cooking time and baste the steak with it a few times before finishing.
- If you like spice, add a few slices of pickled jalapeños to the sandwich or a dash of hot sauce to the mustard mayo.
- Ribeye or flank steak work well, too. Adjust the cooking times depending on the thickness of the steak.
Suggested Menus
Here are three delicious menu ideas, perfect for any occasion, from casual lunches to cozy date nights at home.
Casual Weekend Lunch Menu
- Main: Steak Sandwich
- Side: Crispy potato wedges
- Salad: Fresh salad greens with a lemon vinaigrette
- Drink: Iced tea or a light lager
- Dessert: Mixed fresh fruit
Game Day Feast Menu
- Main: Steak Sandwich
- Appetizer: Warm artichoke dip with tortilla chips
- Side: Loaded baked potato casserole
- Drink: Cold beer or sparkling water
- Dessert: Outrageous chocolate cookies or brownies
Date Night
- Main: Steak Sandwich
- Side: Parmesan truffle fries or roasted Brussels sprouts
- Salad: Mixed greens with goat cheese and walnuts, with a balsamic dressing
- Drink: Red wine, such as a Cabernet Sauvignon
- Dessert: Molten chocolate cake or tiramisu
How to Store the Leftovers
If you have leftovers (unlikely!), wrap them tightly in foil or plastic wrap and refrigerate. The steak can be stored separately in an airtight container for up to 3 days. To reheat, warm the steak in a skillet over medium heat or in the oven. Avoid microwaving to prevent the steak from becoming chewy.
More Recipes You’ll Like
Mediterranean Pressed Sandwich
Oven Baked Tuna Melt Sandwich
Tea Sandwiches
Chicken Bacon and Mushroom Sandwich
Questions About Steak Sandwich with Grilled Onions
You can prepare the steak and caramelize the onions a day in advance. Keep them stored separately in airtight containers in the fridge, then reheat and assemble the sandwiches right before serving.
Definitely. While ciabatta or French bread works best due to its sturdiness, you can also use baguettes, sourdough, or even soft rolls.
Some other topping suggestions include sautéed mushrooms, roasted bell peppers, or fresh tomato slices.
Have a question or thought to share?
If you have a question about the recipe or if you’ve made it and want to share how it turned out, I would truly enjoy hearing from you. Just scroll down to leave a comment or add your star rating.
Thank you for stopping by. It means a lot to have you here.
Recipe
Want to save this recipe?
Enter your email below and get it sent straight to your inbox.
Steak Sandwich with Grilled Onions
Ingredients
For the Mustard Mayo:
- ⅓ cup mayonnaise
- 1 tablespoon whole-grain mustard
- 2 tablespoons Dijon mustard
- 2 tablespoons sour cream
- ⅛ teaspoon kosher salt
For the Steak Sandwich:
- 12 ounces New York strip steak
- kosher salt
- black pepper
- 2 ½ tablespoon olive oil divided use
- 2 yellow onions sliced in rings
- ½ teaspoon fresh thyme leaves
- 2 ciabatta buns or baguette, Italian loaf, or other rustic bread
- ½ cup baby arugula
Instructions
Make the Mustard Mayo Sauce
- Stir all ingredients for the sauce together in a small bowl and set it aside until needed.⅓ cup mayonnaise, 1 tablespoon whole-grain mustard, 2 tablespoons Dijon mustard, 2 tablespoons sour cream, ⅛ teaspoon kosher salt
Prep and Cook the Steak
- Season the steak liberally with salt and pepper on both sides.12 ounces New York strip steak, kosher salt, black pepper
- Heat the olive oil in a medium skillet over high heat until it's almost smoking.1 tablespoon olive oil
- Add the seasoned steak to the hot pan and sear on each side for about a minute.
- Reduce the heat to low and cook the steak for about 7 to 10 minutes for rare, and up to 15 minutes for well done.
- When the cooking time is finished, remove it to a plate and cover tightly with foil. Allow the steak to rest for 10 minutes while you cook the onions.
Make the Caramelized Onions
- Using the same pan without cleaning it, heat the remaining olive oil over medium heat.1 1/2 tablespoons oive oil
- Add the onion and thyme and saute, stirring often, for about 10 minutes or until the onions are brown and caramelized.2 yellow onions, ½ teaspoon fresh thyme leaves
Assemble the Sandwiches
- Slice the steak on an angle across the grain.
- Spread the mustard-mayo sauce on top and bottom of the bread.2 ciabatta buns
- Place a layer of steak strips on the bottom of the bun, sprinkle with salt and pepper, and top with the caramelized onions.
- Place baby arugula on top of the onions and cover the sandwich with the top half of the bun.½ cup baby arugula
Notes
- You’ll have the best results if you start with a steak that’s at room temperature.
- The pan should be very hot for the searing step. I use a cast iron skillet because it gets really hot and holds the heat for a long time.
- When cooking the onions, stir them often making sure you turn them over frequently so they all cook evenly and turn a golden, caramel brown.
Nutrition Information
Nutrition information is calculated by software based on the ingredients in each recipe. It is an estimate only and is provided for informational purposes. You should consult your healthcare provider or a registered dietitian if precise nutrition calculations are needed for health reasons.
I’m Lana Stuart, an award-winning cookbook author, food blogger, and lifelong cook raised deep in Southwest Georgia. I started Lana’s Cooking in 2009 to share the tried-and-true recipes I grew up with. Around here, the food is full of flavor, the traditions run deep, and there’s always room at the table.
Have mercy……
You had me when I saw the word “steak”.