Description
These Buttery Roast Beef Sliders with Caramelized Onions are indulgent, flavorful mini sandwiches perfect for gatherings or a comforting meal. They feature tender roast beef, melty cheese, sweet caramelized onions, and a homemade garlic aioli, all packed into soft slider buns and brushed with a savory garlic butter sauce. Served warm with rich au jus for dipping, these sliders combine layers of taste and texture that will delight any sandwich lover.
Ingredients
Scale
Caramelized Onions
- 2 tablespoons unsalted butter
- 1 tablespoon olive oil
- 3 large yellow onions, thinly sliced
- ½ teaspoon kosher salt
- 1 teaspoon brown sugar
- 2 tablespoons beef broth
Homemade Garlic Aioli
- 1 large egg yolk, room temperature
- 1 teaspoon Dijon mustard
- 1 garlic clove, finely grated or minced
- 1 tablespoon fresh lemon juice
- ½ cup light olive oil or neutral oil
- Kosher salt, to taste
Au Jus Sauce
- ¼ cup unsalted butter
- 1 tablespoon Better than Bouillon Beef Base
- 2 cups beef broth
- 2 teaspoons Worcestershire sauce
Roast Beef Sliders
- 12 slider buns, sliced in half (preferably Hawaiian rolls)
- ¼ cup homemade garlic aioli or mayonnaise
- ½ pound deli roast beef, thinly sliced
- 12 slices melty cheese (provolone, Swiss, or muenster)
- ½ cup shredded mozzarella cheese
- 2 cups caramelized onions
Garlic Butter Sauce
- 6 tablespoons unsalted butter, melted
- 1 teaspoon Worcestershire sauce
- 1 tablespoon poppy seeds
- 1 tablespoon white sesame seeds
- ½ tablespoon garlic powder
- ½ tablespoon dried minced onion
- ½ teaspoon kosher salt
- Freshly cracked black pepper, to taste
Instructions
- Make the Caramelized Onions: Melt the butter and olive oil in a large skillet over medium-low heat. Add the thinly sliced onions, sprinkle with kosher salt and brown sugar, and cook low and slow for about 45 minutes, stirring occasionally, until the onions are soft, deep golden brown, and jammy. At the end, stir in the beef broth to deglaze the pan, then set aside.
- Make the Garlic Aioli: In a small bowl, whisk together the egg yolk, Dijon mustard, grated garlic, and fresh lemon juice until smooth. Slowly stream in the oil while whisking or using an immersion blender until the mixture thickens into a creamy aioli. Season with kosher salt to taste and set aside. (Alternatively, mix mayonnaise with garlic, mustard, lemon juice, and salt for a quicker version.)
- Prepare the Au Jus Sauce: Melt the butter in a medium saucepan over medium heat. Stir in the Better than Bouillon beef base, beef broth, and Worcestershire sauce. Let the mixture simmer gently for 20 minutes until it reduces by half and slightly thickens. Keep warm until serving.
- Toast the Bottom Buns: Preheat the oven to 350°F. Slice the slider buns in half horizontally without separating them. Place the bottom halves on a parchment-lined baking sheet, brush lightly with melted butter or garlic aioli, and toast in the oven for 5 minutes until just golden.
- Assemble the Sliders: Spread a generous layer of garlic aioli over the toasted bottom buns. Pile the thinly sliced roast beef over the buns in 2 to 3 layers. Lay down the slices of melty cheese evenly over the beef, then sprinkle with shredded mozzarella for extra meltiness. Spoon an even layer of caramelized onions over the cheese.
- Butter the Top Buns and Bake: Place the top halves of the rolls on the sliders. In a small bowl, mix the melted butter, Worcestershire sauce, poppy seeds, white sesame seeds, garlic powder, dried minced onion, kosher salt, and freshly cracked black pepper. Generously brush this garlic butter sauce on top of the rolls. Loosely cover the sliders with foil and bake for 10 minutes. Remove the foil and bake for another 10 minutes until the tops are golden brown and the cheese has melted fully.
- Serve: Slice between the rolls to separate the sliders. Serve warm with small bowls of au jus on the side for dipping. Enjoy your rich and flavorful buttery roast beef sliders!
Notes
- For a quicker version, use mayonnaise seasoned with garlic, mustard, and lemon juice instead of homemade aioli.
- If short on time, bake the sliders without the caramelized onions and use mayo to make easy roast beef sliders in about 30 minutes.
- Make sliders up to two days ahead without topping with caramelized onions or garlic butter; add these just before baking.
- Store leftovers in an airtight container for up to 3 days.
- Reheat leftovers in the oven at 375°F for about 10 minutes to prevent sogginess.
- Sweet Hawaiian rolls work best for soft, slightly sweet slider buns.
- Use beef broth to deglaze caramelized onions to enhance the depth of flavor.
Nutrition
- Serving Size: 1 slider
- Calories: 350 kcal
- Sugar: 3 g
- Sodium: 550 mg
- Fat: 22 g
- Saturated Fat: 10 g
- Unsaturated Fat: 10 g
- Trans Fat: 0 g
- Carbohydrates: 25 g
- Fiber: 1 g
- Protein: 18 g
- Cholesterol: 85 mg
