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Hot roast beef sandwich with onion jam featured image.
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4.91 from 10 votes

Hot Roast Beef Sandwiches with Onion Jam

Hot roast beef sandwiches with layers of shaved roast beef on garlic rolls topped with melted mozzarella and a homemade onion jam.
Prep Time5 minutes
Cook Time30 minutes
Total Time35 minutes
Course: Main Course
Cuisine: Italian
Servings: 4 sandwiches


For the garlic rolls

  • 8 tablespoons unsalted butter
  • 1/4 cup olive oil
  • 5 cloves garlic grated
  • 1/4 teaspoon crushed red pepper flakes optional
  • 1/4 cup flat-leaf Italian parsley minced
  • salt to taste
  • 4 large hard rolls
  • 3 tablespoons Pecorino Romano grated

For the onion jam

  • 1/4 cup olive oil
  • 3 large sweet onions diced, about 2 pounds
  • 1/2 teaspon kosher salt
  • 3/4 cup sugar
  • 1 cup balsamic vinegar
  • 1/2 teaspoon dried thyme

For the sandwiches

  • 4 large garlic rolls from above
  • 1 pound roast beef sliced thin or shredded
  • 1/2 pound mozzarella cheese sliced
  • 1 cup onion jam from above


For the garlic rolls

  • Preheat oven to 350f and set the first rack in the middle and the other rack to the top 1/3 of the oven.
  • Saute the garlic in the butter and oil for 2-3 minutes over medium-low heat or until fragrant. Turn off the heat and add in the crushed red pepper flakes and parsley along with a pinch of salt (to taste).
  • Cut the rolls open and distribute the garlic butter all over the inside of each roll. Sprinkle with the Pecorino then place the rolls on a baking sheet and cover with foil.
  • Bake for 12 minutes on the lower rack then remove the foil and move the bread to the higher rack. Broil for 1-3 minutes or until the bread is golden around the sides and sizzling but not burnt. Watch the whole time and be prepared to remove it quickly.

For the onion jam

  • Saute the onions in olive oil over medium heat until golden (about 15 minutes).
  • Add the salt, sugar, balsamic vinegar, and thyme. Cook for another 10 minutes or until the jam has thickened.
  • Taste test and adjust salt, pepper, and sugar levels to taste. Pour the jam into a bowl and set aside.

For the sandwiches

  • Place the roast beef then top with mozzarella on the bottom half of each roll, dividing evenly. Place just the bottom sides onto a baking sheet and broil until the cheese melts (about 2-3 minutes). Watch carefully!
  • Spread the onion jam on top of the sandwiches then place the top rolls onto the sandwich. Enjoy!



  • 3/4 cup of sugar will yield a moderately sweet onion jam. Feel free to use more or less sugar to taste. 
  • Leftovers can be saved in the fridge for up to 3 days and can be reheated in the oven wrapped in foil at 350f until warm.


Calories: 1117kcal | Carbohydrates: 82.4g | Protein: 56.7g | Fat: 63.7g | Saturated Fat: 27g | Cholesterol: 199mg | Sodium: 624mg | Potassium: 733mg | Fiber: 3.7g | Sugar: 44.6g | Calcium: 535mg | Iron: 24mg