These steak sandwiches are the ultimate lunch (or dinner) recipe. Loaded with homemade roasted garlic butter, caramelized onions, crispy bacon, tender, perfectly-cooked steak, avocado, cheese, arugula, and pepperoncinis, this recipe takes the word sandwich to a whole new level!

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This recipe is…
Cassy’s brother-in-law, Winston, is responsible for this unbelievably delicious sandwich recipe. Cassy first tried it on a family trip to Florida and came back to the Fed & Fit office after their trip RAVING about it. Fast forward to photo shoot day, and the entire team understood exactly what the hype was all about …this sandwich is SO GOOD!
Close your eyes and picture this: crusty, delicious bread slathered with homemade roasted garlic butter and then layered with tender, mouthwatering steak, crispy bacon, caramelized onions, melted white cheddar cheese, arugula, avocado, and pepperoncinis. It’s the tastiest darn sandwich you’ll ever sink your teeth into!
Looking for more flank steak recipes? We’ve got several! This garlic butter steak and potatoes skillet is so simple and satisfying, and these Thai-inspired beef salads and Mediterranean steak bowls are the perfect meal prep lunch recipes!
Why You’ll Love This Recipe
- It’s big on flavor – did you see the list of ingredients in this sandwich? Sweet caramelized onions, salty bacon, nutty, rich roasted garlic, tangy pepperoncinis, tender, perfectly seasoned (and cooked) steak – the flavors are big, complex, and delicious.
- It’s perfect for lunch or dinner – this recipe is a great one to meal prep for lunch (though you may wait to assemble the sandwiches to keep the bread from getting soggy) or serve for a family-friendly or party guest-worthy dinner.
Steak Sandwich Recipe Ingredients
The ingredient list may feel a little long for a sandwich recipe, but I promise every single thing on the list adds to the flavor and WOW-factor of this recipe. Find ingredient notes (including substitutions and swaps) below.
- Flank steak – if you’re cooking the steak from scratch, just for these sandwiches, feel free to use flank or skirt steak here. If you happen to have leftover steak hanging around, feel free to slice it and use it (flank, steak, sirloin, or ribeye will all work).
- Cheese – Winston swears by Trader Joe’s Unexpected Cheddar for this recipe, so if Trader Joe’s is on your list of places to stop by, feel free to grab a block! Otherwise, any sharp white cheddar will work great.
- Bread – we used gluten free rolls for this recipe, but you can absolutely use any bread (gluten free or not) that you love.
A full ingredient list with exact amounts can be found in the recipe card below.
Recipe Variations and Modifications
- Add some spice – swap the pepperoncinis for fresh or pickled jalapeños. Trader Joe’s also makes yummy crispy jalapeños that would be tasty here!
- Caramelize the onions in bacon fat – add another layer of flavor to this recipe by caramelizing the onions in bacon fat. To do this, simply use a rimmed baking sheet to cook the bacon in the oven, and once it’s done, pour the grease into a pot for the onions.
How to Make the Best Steak Sandwich
While there are a bunch of components to this sandwich recipe, they’re all incredibly easy to pull off! Follow along below for the full how-to.
Step 1: Set the butter out to soften. Preheat the oven to 350°F. Cut the end of each garlic bulb off and coat in olive oil and sprinkle with salt. Wrap the bulbs in foil and place in the oven for 1 hour. Once cool to the touch, squish each clove of garlic out into a bowl with the softened butter, and macerate the garlic with a fork, combining it with the butter. Set aside to use for later.
Step 2: While the garlic roasts, place 4 tablespoons of oil in a preheated cast iron pan, turn the heat to low and place the thinly sliced onions in the pan. Slowly cook the onions, stirring occasionally, until they’re a golden color (about 45 minutes).
Step 3: When the onions have about 25 minutes left, season the steak with the garlic powder, onion powder, salt, cumin, paprika, and black pepper.
Step 4: Heat 2 tablespoons of olive oil in another skillet over high heat. Once hot, add the steak and sear for 4-5 minutes. Flip the steak, and continue cooking until a meat thermometer inserted into the thickest part of the steak reads 140°F. Remove the steak from the pan and let it rest until it comes to 145°F. Then, slice it against the grain.
Step 5: Assemble the sandwiches by slathering the garlic butter on each slice of bread. Sprinkle the cheese on top of the buttered bread, and broil until the cheese is melted.
Step 6: Layer the steak, caramelized onions, bacon and bacon one one side of the bread and the arugula, pepperoncinis, and sliced avocado on the other side of the bread. Place the two halves together, and enjoy!
Recipe Tips
- Don’t overcook your steak – grab a meat thermometer if you don’t have one already (we love this thermometer that can be used WHILE you cook vs. having to manually check the temperature every so often). Using a thermometer will ensure that your steak is perfectly cooked and not tough or dry.
- Make extra caramelized onions – while caramelized onions are really easy to make, they are quite time intensive. The flavor they add to any recipe is irreplaceable, though. All that said, doubling or even tripling the amount of onions you caramelize for this recipe is a great way to save time (and add flavor) in the future. Store them in an airtight container in the fridge or freezer and then use them for BBQ chicken pizza or any other recipe that would benefit from the flavorful addition!
How to Serve
Serve your steak sandwiches alongside chips, potato wedges, fruit salad, or, if you’re looking for a simple green salad to add, this arugula side salad.
How to Store
Store leftover sandwiches in an airtight container in the fridge for up to 3 days. Know that when you eat your leftovers, they may be slightly soggy, though (this is the nature of a leftover sandwich!).
IF you plan on prepping these sandwiches for a week’s worth of lunches, store each component in its own container in the fridge, then assemble on the day-of. This will allow you to heat the parts of the sandwiches that are best warm (buttered cheesy bread, steak, bacon, and caramelized onions), keep the cold parts of the sandwich cold (arugula, pepperoncinis, and avocado), and will make for a better (read: less soggy) experience overall.
Frequently Asked Questions
Flank steak and skirt steak both work really well here! That said, if you have leftover ribeye or sirloin steak, you could absolutely slice it up and use it.
Winston swears by Trader Joe’s Unexpected Cheddar for this recipe, so if Trader Joes is on your list of places to stop by, feel free to grab a block! Otherwise, any sharp white cheddar will work great.
More Favorite Lunch Recipes
If you tried this steak sandwich or any other recipe on my website, please leave a 🌟 star rating and let me know how it went in the 📝 comments below!
Steak Sandwich Recipe with Caramelized Onions and Bacon
Ingredients
- 2 bulbs garlic
- 1 sticks (½ cup or 8 tablespoons) butter, softened
- 6 tablespoons olive oil, divided
- 2 medium yellow onions, thinly sliced
- 1-2 pounds flank steak
- 2 tablespoons garlic powder
- 2 tablespoons onion powder
- salt
- 1 tablespoon cumin
- 1 tablespoon paprika
- black pepper
- 4 medium-sized rolls, cut in half (or one large loaf of bread)
- 1½ cups sharp white cheddar, shredded
- 8 slices bacon, cooked until crispy
- 2 cups arugula
- ½ cup pepperoncinis, sliced
- 1 medium avocado, sliced
Instructions
- Set the butter out to soften.
- Preheat the oven to 350°F. Cut the end of each garlic bulb off and coat in olive oil and sprinkle with salt. Wrap the bulbs in foil and place in the oven for 1 hour.
- Once cool to the touch, squish each clove of garlic out into a bowl with the softened butter, and macerate the garlic with a fork, combining it with the butter. Set aside to use for later.
- While the garlic roasts, place 4 tablespoons of oil in a preheated cast iron pan, turn the heat to low and place the thinly sliced onions in the pan. Slowly cook the onions, stirring occasionally, until they're a golden color (about 45 minutes).
- When the onions have about 25 minutes left, season the steak with the garlic powder, onion powder, salt, cumin, paprika, and black pepper.
- Heat 2 tablespoons of olive oil in another skillet over high heat. Once hot, add the steak and sear for 4-5 minutes. Flip the steak, and continue cooking until a meat thermometer inserted into the thickest part of the steak reads 140°F. Remove the steak from the pan and let it rest until it comes to 145°F. Then, slice it against the grain.
- Assemble the sandwiches by slathering the garlic butter on each slice of bread. Sprinkle the cheese on top of the buttered bread, and broil until the cheese is melted.
- Layer the steak, caramelized onions, and bacon one one side of the bread and the arugula, pepperoncinis, and sliced avocado on the other side of the bread. Place the two halves together, and enjoy!