Hot roast beef sandwiches with onion jam might just be the tastiest sandwich we've ever eaten! Layers of shaved roast beef are piled on top of garlic rolls and topped with melted mozzarella and a homemade sticky-sweet onion jam to seal the deal.
We love a good roast beef sandwich, and this one is the king of all roast beef sandwiches.
There's something so good about the combination of ultra-thin shaved roast beef on top of garlic bread with melted mozzarella.
But the onion jam used for this roast beef sandwich recipe just takes it over the top!
How to make it
Each number corresponds to the numbered written steps below.
Note: The garlic bread (step 3) can be made at the same time as the onion jam. This will save you time.
- Dice 3 large sweet onions and saute them in ¼ cup of olive oil until golden (about 12-15 minutes).
- Add ¾ cup of sugar, 1 cup of balsamic vinegar, and a ½ teaspoon of dried thyme, and cook for another 10 minutes or until the jam has thickened. Note: I added a sprig of rosemary here because I didn't have thyme, but you could use either one or none depending on your taste.
- Preheat the oven to 350f and set the first rack in the middle and the other rack to the top ⅓ of the oven. Grate 5 cloves of garlic and mince ¼ cup of flat-leaf Italian parsley. Add ¼ cup of olive oil and 8 tablespoons of unsalted butter to a pan and saute the garlic over medium-low heat for 2-3 minutes or until fragrant. Turn off the heat and add ¼ teaspoon of crushed red pepper flakes, if using, and parsley along with a pinch of salt, to taste.
- Slice 4 large kaiser rolls in half and place them on baking sheets lined with foil. Distribute the garlic butter and 3 tablespoons of grated Pecorino Romano cheese all over the insides of each roll. Cover the rolls with foil.
- Bake the rolls 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. Keep a close eye on the rolls while in the broiler to prevent burning.
- By now the jam should be thick and you can taste test and make any adjustments to salt, pepper, or sugar levels.
- Begin to distribute 1 pound (~¼ pound roast beef per sandwich) of shaved or thinly sliced roast beef on the bottom part of the 4 garlic bread rolls, then top with 2-3 slices of mozzarella cheese and broil until the cheese melts (about 2-3 minutes). Again, watch carefully to prevent burning.
- Spread the onion jam on the top half of the sandwiches, then place the top rolls onto the bottom to create the hot roast beef on garlic bread sandwiches. Enjoy!
Top tips for onion jam roast beef sandwiches on garlic bread
- The roast beef. When you get to the deli counter, request that the roast beef be "shaved", rather than thin sliced. Shaved roast beef will give you the best texture for this particular sandwich, but in reality, almost all sandwiches benefit from having the meats thinly sliced.
- Onion jam. The onion jam we've made here is so easy and so good and we strongly recommend making it! It is moderately sweet so if you're looking for something a little less sweet, use less than the ¾ cup of sugar we have in the recipe to start. You can always add a little more at the end if need be. Pictured above is the jam made with a sprig of rosemary but in the past, I've made the jam with a sprig of fresh thyme, or dried thyme as outlined in the recipe card. When I shot these recipe photos we did not have thyme on hand so I used rosemary. Both are great and are up to you if you want to use one or the other, or neither!
- The garlic bread. We used New York deli-style rolls with poppy seeds but if you live in other areas without access to these rolls, look for kaiser or other types of hard round rolls. You could also use hero or sub rolls to make a larger more substantial sandwich. If you'd like to make a full loaf of Italian bread to make these sandwiches, follow our garlic bread recipe. The process to turn the rolls into garlic bread is simple and we do strongly recommend using fresh garlic instead of jarred garlic.
- Toppings. There are many possibilities for hot roast beef sandwich toppings. We've chosen to use deli sliced mozzarella cheese and of course the onion jam! These sandwiches would also be great topped with bacon, blue cheese/gorgonzola, crispy fried onions or shallots, or even pepperoncini. Be creative and most importantly, top with what you like!
More great sandwich recipes
If you love sandwiches as much as we do, here are a few of our most loved sandwich recipes!
- Italian hero - This is the classic hero layered with Italian cold cuts, provolone cheese, lettuce, tomato, onion, and oil and vinegar.
- Pepper and egg sandwich - Eggs, peppers, and if you want, mozzarella cheese on hard round rolls.
- Bacon egg and cheese sandwich - New York deli-style breakfast sandwich that's as authentic as it gets.
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For the garlic rolls
- 8 tablespoons unsalted butter
- ¼ cup olive oil
- 5 cloves garlic grated
- ¼ teaspoon crushed red pepper flakes optional
- ¼ cup flat-leaf Italian parsley minced
- salt to taste
- 4 large hard rolls
- 3 tablespoons Pecorino Romano grated
For the onion jam
- ¼ cup olive oil
- 3 large sweet onions diced, about 2 pounds
- ½ teaspon kosher salt
- ¾ cup sugar
- 1 cup balsamic vinegar
- ½ teaspoon dried thyme
For the sandwiches
- 4 large garlic rolls from above
- 1 pound roast beef sliced thin or shredded
- ½ 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 ⅓ 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!
- ¾ 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.