Steak, Roasted Tomato and Caramelized Onion Sandwich

Grab a pile of napkins because you’re going to need them for this flavor packed Steak, Roasted Tomato and Caramelized Onion Sandwich. 

Steak, Roasted Tomato and Caramelized Onion Sandwich from The Girl In The Little Red Kitchen

The past few weekends Braden and I have resumed our “great walks” of Brooklyn tour.  We pick a spot and walk (while stopping for drink and drink) until our feet can’t carry us anymore.  Sometimes it’s through spots of Prospect Park or for example, this weekend all around Sheepshead Bay, Manhattan Beach and Brighton Beach.  One common thing I’ve noticed on our walks is that the people of Brooklyn are ready for summer, from laying out in the sun, to setting up picnics and parties and to breaking out their grills.

Oh yes, that’s right, we might not have backyards but we grill when we can.  This means the smells of burgers, steaks and sausages float through the air on our walks – which not only makes me hungry but gets me in the mood for what they’re cooking.

Steak, Roasted Tomato and Caramelized Onion Sandwich |

Let’s be honest here though – as good as flank steak  or a burger is plain what makes them stand out is the toppings.  For me my go-to first and for most is caramelized onions.

Sweet, soft, richly flavored, I can eat them by the spoonful and I have no shame in admitting that I have.  My love affair for caramelized onions start a long time ago, from slurping French Onion Soup to my mom cooking with them in all of my favorite dishes growing up.  What can I say? They hold a special place in my food loving heart.

Now while some seared steak with onions on the side is great and all, what’s even better is when they are piled together in a hearty sandwich. A little cheese, some slow roasted tomatoes and pesto take elevate this into a taste of summer sandwich.

Steak, Roasted Tomato and Caramelized Onion Sandwich |

While you can caramelize any type of onion, Vidalia is my personal favorite.  I love the natural sweetness of these onions, they are so sweet in fact there is no need to add a pinch of sugar when cooking them down (a trick I usually use when I don’t have Vidalias on hand).  The reason for the sweetness is because of Georgia’s soil, where Vidalia onions are grown.  They can only be grown in 20 counties in Georgia to actually have the name, and it’s because the number of minutes of daylight during the winter of why Vidalias are so sweet.  Plus fun fact here, all 12,000 acres of Vidalia onions planted each year are done by hand!

Now while true caramelized onions is no quick visit in the kitchen to get dinner on the table, it’s totally worth the wait.  Plus you can caramelize a ton at a time and freeze them to enjoy all summer long.  It’s a good thing Vidalia Onions has a 50 cents off coupon for your next trip to the store to stock up.

Steak, Roasted Tomato and Caramelized Onion Sandwich |

As I mentioned, prep for this sandwich takes time but it’s completely worth it! Plus half the work can be cooked in advance.  Caramelize the onions while you’re working on another task – there’s no need to stand over the stove the entire time anyway.  Those tomatoes can be roasted in advance as well, perhaps when you’re cooking down the onions?

Once all that is out of the way, just pop outside to grill your steak, assemble and enjoy!

For more information on Vidalia Onions visit their website or say hello on Facebook, Twitter, Pinterest, Instagram and Youtube!


Steak, Roasted Tomato and Caramelized Onion Sandwich

15 min

1 hr, 30

1 hr, 45

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  • 2 Vidalia Onions
  • 1 tablespoon unsalted butter
  • 1 tablespoon olive oil
  • 1/2 teaspoon kosher salt
  • 1 tablespoon balsamic vinegar
  • 1 pint cherry tomatoes, halved
  • 1 tablespoon olive oil
  • 2 tablespoons balsamic vinegar
  • 1 teaspoon kosher salt
  • 1 teaspoon black pepper
  • 1 1/2 pounds flank steak
  • kosher salt and black pepper
  • 4 slices swiss or gruyere cheese
  • pesto - any variety: kale , ramp , basil, garlic scape
  • 4 hearty rolls, toasted


  1. Remove the tip and root ends of the onions, cut in half and thinly slice.
  2. In a large cast iron skillet over medium heat melt the butter and add the olive oil. Add the sliced onions to the pan and coat. Let cook over medium heat until the onions start to soften and brown slightly.
  3. Reduce the heat to medium low and continue to saute the onions, stirring them every 5-10 minutes or so scrapping the brown bits from the bottom of the skillet with a wooden spoon. Around 20 minutes the onions should start to look lightly golden brown, around 40 minutes more golden and at 50 minutes they should be a deep color.
  4. After 50 minutes of cooking, add the balsamic vinegar and continue to cook for another 10 minutes. You can continue to cook for are more richer flavor but at this point the onions are finished. Remove from the pan with a slotted spoon and place in a bowl.
  5. While the onions are cooking, heat your oven to 325 degrees and line a rimmed baking sheet with parchment paper. Add the halved cherry tomatoes and toss with olive oil, balsamic vinegar, salt and pepper.
  6. Roast for 40 minutes and let cool to room temperature.
  7. Bring your steak to room temperature before cooking, then season generously with salt and pepper.
  8. If grilling - grill the steak to your desired internal temperature, I recommend medium rare - about 6-7 minutes per side.
  9. If cooking indoors, heat a cast iron skillet over medium high heat and drizzle 1/2 tablespoon oil in the skillet. Cook one side for about 8 minutes and the second side for 6.
  10. Remove the second, tent with foil and let rest for 15 minutes before thinly slicing.
  11. Slice the rolls, and spread pesto on each side of the bread. Line the bottom roll with roasted tomatoes and then 3-4 slices of steak. Top with a piece of swiss cheese and a heaping amount of caramelized onion.
  12. Place the roll on the grill to melt the cheese slightly or in your oven or broiler for 1-3 minutes to melt the cheese.
  13. Top the sandwich and enjoy!
  14. Leftover onions an tomatoes can be stored in the refrigerator for up to one week or frozen for 3 months.
Recipe Type: Main, Sandwich

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This post is sponsored on behalf of  Vidalia Onion.  As always all opinions are my own and thank for supporting brands that I work with. 

Steak, Roasted Tomato and Caramelized Onion Sandwich |

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16 thoughts on “Steak, Roasted Tomato and Caramelized Onion Sandwich

  1. Carla

    Oh my! This is considered a breakfast sandwich, right? Since it’s 9 AM right now 😉 I’m with you on the toppings – I choose my burgers and sandwiches based on toppings, especially if onions are involved!

  2. Courtney @ NeighborFood

    This is my kind of sandwich. I love steak and caramelized onions together, and the roasted tomatoes puts it over the top. The tradition of walking tours is so great. We should do something similar here in Columbus!

  3. Delishogram

    Oh my!!!!
    I am in heaven; beef, swiss cheese and caramelized onions. Where do I sign up????
    I need to eat this!

    I have a food sharing site and really really really need you to submit this recipe!!!! It looks delicious!

  4. Lori @ Foxes Love Lemons

    Caramelizing onions may take a bit of time, but it’s so easy, and SO worth the time! I usually caramelize onions for the next night’s dinner after we eat dinner the night before. This sandwich looks amazing. That perfectly cooked beef and those sweet Vidalias! Love love love!

  5. Amelia @ Eating Made Easy

    I love caramelized onions, but until now didn’t know there was a different between Vidalias and other sweet onions – I thought it was just a varietal that could be grown anywhere. So cool it’s unique to a small part of Georgia! I love food facts like that 🙂

  6. Nichole

    Note to self: don’t read food blogs while dinner is cooking…I want this sandwich now! In other news, I think it’s so cool you can just pick a neighborhood and walk it (and stop fo’ drinks!)- of course living in Florida has its perks, but not like that.


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