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Steak Sandwich with Oven-Roasted Tomatoes on a Brioche Bun

This week we’re putting a salad on our sandwiches and saving ourselves some work! Warm slices of steak on a toasted brioche bun pair perfectly with a cold herbed mustard sauce and oven-roasted tomatoes. Throw on some creamy avocado and crunchy onion, and you’ve got warm, cold, crunchy and creamy all in one place.

You won’t need anything else to satisfy your palette!


  • 6 plum tomatoes, cut into thick slices
  • 6 brioche buns
  • 1 red onion, thinly sliced
  • 3 lbs of sirloin steak
  • 2 avocados, sliced
  • 1 teaspoon of rosemary, minced
  • 1 teaspoon of thyme, minced
  • ½ lemon, juiced
  • ¾ cup of a good dijon mustard (I used the brand Maille)
  • 3 garlic cloves
  • ½ cup of olive oil (to rub on steaks and tomatoes)
  • 1 head of romaine lettuce
  • Salt and pepper to taste



  1. Set oven to broil on high.
  2. Cut tomatoes into thick slices, about ½ inch thick, and assemble on a large sheet pan.
  3. Coat tomatoes with olive oil, and season with salt and pepper.
  4. Cook tomatoes for 4-5 minutes, watching closely so that they don’t burn. Then flip tomatoes, and cook them for an additional 4-5 minutes.


  1. Heat a large pan over high heat.
  2. Rub each piece of sirloin with olive oil, and season each side generously with salt and pepper.
  3. Cook steak for 5-7 minutes per side. Resist the temptation to flip before the time is up so that the steaks can get a nice crust!
  4. When the steaks are finished cooking, allow them to rest on a cutting board for 10 minutes, covered with aluminum foil.
  5. Slice avocados and onions to prepare the toppings!


  1. In a small bowl, combine mustard, rosemary, thyme, garlic, and lemon juice.

To Assemble:

It’s time to put it all together!

  1. Toast brioche buns.
  2. Add herbed mustard to both sides of bread, and top with steak, avocado, onion, roasted tomatoes, and lettuce.
  3. Enjoy!


Photos by Josh Guirguis

Title Image by Josh Guirguis

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