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Toasted Roast Beef Sandwich Recipe

Being a huge fan of patty melts, I took the opportunity recently to make a patty-melt type sandwich from some left-over roast beef.  This toasted roast beef sandwich recipe works well with either sliced cold cut roast beef or left over cuts from a chuck or round roast.  Either produces a lovely sandwich that makes a great week night indulgence for very little time investment.

Toasted Roast Beef Sandwich

Yield: 2 sandwiches

Toasted Roast Beef Sandwich Recipe

A buttery delicious recipe for a toasted roast beef sandwich. Topped with caramelized onions and Swiss cheese, this sandwich is boss.


1 tablespoon light olive oil
1 small onion, thinly sliced
1/2 teaspoon kosher salt
1 cup thinly sliced or shredded roast beef
4 slices of Swiss or Emmentaler cheese
4 slices sour dough bread
2 tablespoons unsalted butter, softened


  1. Place the olive oil in a skillet over medium high heat and add the onions and the kosher salt.
  2. Cook the onions for 10-15 minutes slowly, stirring often.  The goal here is to caramelize the onions so you want to do that by slowly coaxing the sugars out of the onion so that the onion turns soft and a pale golden brown color.  Trying to caramelize an onion over heat that’s too high will results in bitter, burnt onions.
  3. While the onion is caramelizing, butter one side of each piece of bread.
  4. When the onions are as soft and golden brown as you’d like, stir in the beef.
  5. Stir until the beef is cooked all the way through, about 2 minutes or so. Turn off the heat and set aside for now.
  6. Using a separate large skillet on medium high heat, place two pieces of bread butter-side down. Add one slice of cheese and spoon half the beef/onion mixture carefully onto each piece of bread.
  7. Top that with the second piece of cheese and the other slice of bread, butter side up.
  8. Cook until the first side is golden brown, 3-5 minutes.
  9. Flip the sandwich and repeat.  The sandwich should be crispy and golden brown on both sides.
  10. Cut each sandwich on the diagonal and serve.

Prep:10 min

Cook:25 min

Total:35 min

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