Description
These Buttery Roast Beef Sliders with Caramelized Onions deliver a perfect balance of savory meat, melty cheeses, and sweet, jammy onions all layered in soft slider buns. Enhanced with a homemade garlic aioli and a rich au jus dipping sauce, these sliders are an impressive yet easy option for game day, parties, or family dinners.
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 (Hawaiian rolls preferred)
- 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 sliced onions, sprinkle in the kosher salt and brown sugar, and cook slowly for 35–45 minutes, stirring occasionally, until the onions are soft, deeply golden brown, and jammy. Stir in the beef broth at the end to deglaze the pan and incorporate all the flavorful bits. Set aside.
- Make the Garlic Aioli: In a small bowl, whisk together the egg yolk, Dijon mustard, grated garlic, and lemon juice until smooth. While blending with an immersion blender or whisk, slowly stream in the oil until the mixture thickens to a creamy aioli. Season with a pinch of kosher salt and set aside. For an easier version, mix garlic, mustard, lemon juice, and salt into mayonnaise instead.
- 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 it simmer for 15–20 minutes until reduced by about half. The sauce will darken and thicken slightly as it cools. Keep warm until serving.
- Toast the Bottom Buns: Preheat the oven to 350°F. Slice the buns horizontally without separating the halves. Lay the bottom halves cut-side up on a parchment-lined baking sheet. Lightly brush with melted butter or 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. Layer the thinly sliced roast beef evenly across the buns, stacking 2–3 layers for hearty sliders. Place slices of your chosen melty cheese on top, then sprinkle the shredded mozzarella over for extra meltiness. Spoon an even layer of the caramelized onions across the sliders.
- Top and Bake the Sliders: Place the top halves of the rolls on the sliders. In a small bowl, combine 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 mixture over the tops of the rolls. Cover loosely with foil and bake for 10 minutes. Remove the foil and bake for another 5–10 minutes until the tops are golden brown and the cheese is fully melted.
- Serve and Enjoy: Carefully slice between the rolls to separate the sliders. Serve warm with individual bowls of the au jus sauce for dipping.
Notes
- For a quicker 30-minute version, use mayonnaise mixed with the garlic aioli ingredients and omit the caramelized onions.
- Make the sliders up to two days ahead without the caramelized onions and garlic butter, assembling and baking just before serving.
- Store leftovers in an airtight container in the refrigerator for up to 3 days.
- Reheat leftovers in the oven at 375°F for about 10 minutes to keep the buns from becoming soggy.
- Using Hawaiian rolls is preferred for their perfect soft and sweet texture that complements the flavors.
- The homemade garlic aioli can be made richer by using light olive oil; neutral oil can be used for a lighter flavor.
Nutrition
- Serving Size: 1 slider
- Calories: 350 kcal
- Sugar: 4 g
- Sodium: 600 mg
- Fat: 22 g
- Saturated Fat: 11 g
- Unsaturated Fat: 9 g
- Trans Fat: 0 g
- Carbohydrates: 25 g
- Fiber: 2 g
- Protein: 18 g
- Cholesterol: 75 mg
