Name: Roast Beef Sliders with Caramelized Onions and Horseradish Recipe
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: American
Ingredients: 1 lb thinly sliced roast beef; 12 soft slider buns; 8 oz Swiss or provolone cheese, sliced; 1 cup caramelized onions (about 2 medium onions); 1/2 cup beef broth; 2 tbsp horseradish sauce

Jump to Recipe·Print Recipe· 3.9 from 27 reviews

If you’re craving a crowd-pleaser that’s packed with flavor, then this Roast Beef Sliders with Caramelized Onions and Horseradish Recipe is going to be your new go-to. Imagine tender, thinly sliced roast beef nestled inside soft, pillowy slider buns, topped with sweet, deeply caramelized onions, melty Swiss or provolone cheese, and a zingy drizzle of horseradish blended into savory beef broth. It’s a perfect bite-sized sandwich that balances richness, sweetness, and just the right amount of spicy kick that will have everyone asking for seconds.

Roast Beef Sliders with Caramelized Onions and Horseradish Recipe - Recipe Image

Ingredients You’ll Need

This recipe is wonderfully straightforward, relying on a handful of essential ingredients that come together to create an unforgettable flavor profile. Each ingredient plays a key role, whether adding a tender texture, a burst of savory goodness, or that irresistible melty cheese factor.

1 lb thinly sliced roast beef: Choose good quality deli roast beef for tender, ready-to-eat slices that build the hearty base of the sliders.
12 soft slider buns: Soft and slightly sweet buns cradle the fillings perfectly without overpowering the flavors.
8 oz Swiss or provolone cheese: These cheeses melt beautifully and add a creamy, mild taste that complements the roast beef.
1 cup caramelized onions (about 2 medium onions): Slowly cooked onions add a rich sweetness that balances the beef and horseradish.
1/2 cup beef broth: Adds moisture and deep, savory notes when mixed with the horseradish sauce.
2 tbsp horseradish sauce: Provides a bright, peppery contrast that lifts the whole slider experience.

How to Make Roast Beef Sliders with Caramelized Onions and Horseradish Recipe

Step 1: Preheat the Oven and Prep Slider Buns

Start by setting your oven to 350°F (175°C) so it’s ready to go. While it heats, slice your soft slider buns horizontally, making sure they stay intact so they handle the fillings without falling apart. Line them up on a baking sheet with parchment paper for easy cleanup and even baking.

Step 2: Layer Roast Beef on the Bottom Buns

Take your thinly sliced roast beef and pile a generous amount onto the bottom half of each slider bun. This creates that hearty, savory foundation your taste buds will love.

Step 3: Add Cheese and Caramelized Onions

Next, scatter the melty Swiss or provolone cheese slices over the roast beef, then spoon on your beautifully caramelized onions. The combination here is simply irresistible—sweet onions soften the bold bite of the beef and creamy cheese.

Step 4: Mix Beef Broth with Horseradish Sauce and Drizzle

In a small bowl, whisk together the beef broth and horseradish sauce until smooth. This mixture adds moisture, keeps the sliders juicy, and brings a subtle spicy kick. Drizzle this evenly over the layered sliders, making sure every bite will have that perfect balance of flavors.

Step 5: Top and Bake Until Melty and Warm

Place the top halves of the slider buns onto each sandwich, gently pressing them down. Pop the whole tray into the oven and bake for about 15-20 minutes. You’ll know it’s done when the cheese is melted to luscious perfection and everything is warmed through.

How to Serve Roast Beef Sliders with Caramelized Onions and Horseradish Recipe

Garnishes

Keep it simple with classic garnishes like thinly sliced pickles or fresh arugula for a peppery crunch. A sprig of fresh thyme on the side also adds a lovely aroma that complements the caramelized onions beautifully.

Side Dishes

These sliders love company! Serve them with crispy oven fries, a vibrant coleslaw, or even a tangy cucumber salad to brighten the plate. Each side helps round out the meal and adds textural contrast to those soft slider bites.

Creative Ways to Present

If you’re feeling a bit fancy, stack the sliders on a wooden board layered with parchment paper for a rustic look. Alternatively, skewer mini pickles or olives on top of each slider with cocktail picks—it adds flair and keeps the layers together for easy serving at gatherings.

Make Ahead and Storage

Storing Leftovers

If you have any leftovers, store the sliders in an airtight container in the refrigerator for up to 3 days. This keeps the buns soft and the roast beef flavorful. To avoid soggy buns, consider separating the tops and bottoms if you plan to reheat.

Freezing

You can freeze the sliders by wrapping each one individually in plastic wrap, then placing them in a freezer-safe bag or container. They’ll keep well for up to 1 month. Just thaw them in the fridge overnight before reheating.

Reheating

For best results, reheat your roast beef sliders in an oven or toaster oven at 350°F (175°C) for about 10-15 minutes until warmed through and the cheese is melty again. Avoid microwaving if possible, as it can make the buns chewy.

FAQs

Can I use other types of cheese besides Swiss or provolone?

Absolutely! Cheeses like mozzarella or cheddar can work nicely, but keep in mind they will alter the flavor slightly. Swiss and provolone are classic choices because they melt well and complement the roast beef’s flavor perfectly.

How do I caramelize onions properly for this recipe?

Patience is key! Slice the onions thinly and cook them low and slow in a bit of oil or butter over medium-low heat, stirring occasionally until they turn a golden brown and become sweet and soft. This usually takes about 30-40 minutes.

Is there a way to make these sliders vegetarian?

While this particular recipe is designed for roast beef, you could substitute with grilled portobello mushrooms or a smoky tempeh and keep the caramelized onions and horseradish sauce for a similar depth of flavor and texture.

Can I prepare the caramelized onions ahead of time?

Yes! Caramelized onions store very well in the fridge for up to 5 days. Making them ahead saves you time when assembling the sliders and actually deepens their flavor as they rest.

What’s the best way to serve these at a party?

Arrange them on a large platter with small cocktail picks, so guests can easily grab and enjoy. Pair them with a variety of dips, pickles, and sides for a festive, finger-food friendly presentation.

Final Thoughts

This Roast Beef Sliders with Caramelized Onions and Horseradish Recipe is truly one of those dishes that feels like a warm hug on a plate. It’s simple enough to prepare on a busy day but impressive enough to share at any get-together. I encourage you to try making these sliders because once you do, they’re bound to become a beloved staple in your recipe box for every occasion.