French Onion Roast Beef Sliders Recipe

I’m obsessed with this recipe because it combines the perfect blend of sweet and savory flavors, thanks to those heavenly caramelized onions and gooey provolone cheese. Plus, the sliders are super easy to share, making them the ultimate party snack that keeps everyone coming back for more!

I enjoy changing timeless tastes into something new, and these French Onion Roast Beef Sliders are a prime example. They pair fall-apart-tender roast beef with caramelized onions amped up with Worcestershire sauce, creating a dish that is as close to a savory experience as you can get.

Melted provolone takes the place of the traditional French onion soup top, and with thyme, you’ve got an unstoppable sandwich.

Ingredients

Yellow Onions
High in antioxidants; impart a sweet, caramelized flavor.

Worcestershire Sauce
Intensifies umami; adds piquant, savory flavor.

Roast Beef
Excellent source of protein; serves as a robust, flavor-packed element.

Provolone Cheese
The texture is creamy; the flavor mildly sharp; the overall experience is one of richness.

Thyme Leaves
Aroma of herbs; subtle earthiness; enhances flavor complexity.

Slider Buns
Offer carbohydrates; somewhat sugary; tender, light, and comforting texture.

Dijon Mustard
Piquant, somewhat peppery; intensifies taste with gentle warmth.

Ingredient Quantities

• 1 package (12-count) of slider buns or Hawaiian rolls
• 2 tablespoons unsalted butter
• 2 large yellow onions, thinly sliced
• 1 tablespoon Worcestershire sauce
• 1 teaspoon sugar
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 3/4 pound thinly sliced roast beef
• 8 slices of provolone cheese
• 1/4 cup mayonnaise
• 2 tablespoons Dijon mustard
• 1 tablespoon fresh thyme leaves
• 1/4 cup beef broth
• 2 tablespoons melted butter (for brushing on top)
• 1 tablespoon sesame seeds (optional, for garnish)

Instructions

1. Set your oven to 350°F (175°C).

2. A large skillet is used to melt unsalted butter over medium heat. Sliced onions that are thin and not thick are added to the skillet. They are sautéed in the skillet until they caramelize, which should take 20-25 minutes. The task of stirring them and watching them closely is assigned to one person. This person has a good relationship with the skillet and the onions and does not mind spending 20-25 minutes attending to them.

3. Cut through the full package of slider buns in half along the horizontal plane, maintaining their integrity. Put the bottom half of the buns into an oven-safe baking dish.

4. Apply a coating of mayonnaise to the lower half of the buns. Over the mayonnaise, layer Dijon mustard.

5. Evenly lay the roast beef over the bottom buns. Layer the roast beef with the caramelized onions on top of it.

6. Evenly distribute provolone cheese slices over the onions. Ensure that the provolone cheese covers both the onions and the beef evenly.

7. Position the top half of the slider buns atop the layers.

8. Stir the beef broth and melted butter together in a small bowl. Gently pour this mixture over the sliders, allowing the buns to soak in it.

9. If you are using them, sprinkle the tops with sesame seeds and fresh thyme leaves.

10. In the preheated oven, the foil-covered baking dish bakes for 15 minutes. The next step is to take the foil off (be careful, because the trapped steam is hot) and give the sliders an additional 5 minutes in the oven. They’re done when the cheese is melted and the tops are a lovely golden brown. Slice into individual sliders, serve warm, and watch them disappear.

Equipment Needed

1. Oven
2. Large skillet
3. Knife
4. Cutting board
5. Oven-safe baking dish
6. Small bowl
7. Stirring utensil (such as a wooden spoon)
8. Foil
9. Measuring spoons
10. Measuring cups

FAQ

• Q: Can I use a different type of cheese instead of provolone?Q: Are there exist great alternatives to complement the flavors well, like Swiss Cheese or Mozzarella?
• Q: How do I store leftover sliders?A: Encase them securely in aluminum foil or keep them in an airtight container in the refrigerator for not more than 3 days.
• Q: Can I make these sliders ahead of time?
  A: Yes, you can prepare the onions and assemble the sliders, then bake them just before serving.
• Q: Is it necessary to use sugar when caramelizing the onions?A: Caramelization is enhanced by sugar; it makes things sweet and gives them color. But you can leave it out if you want.
• Q: Can this recipe be doubled for a larger crowd?Q: You could double the ingredients and use two pans to make more sliders, right?
• Q: Are the sesame seeds necessary as a garnish?No, they’re not required; you can leave them off if you want a less textured surface on top.

Substitutions and Variations

Hawaiian rolls or slider buns: Use small dinner rolls or mini brioche buns in their place.
Provolone cheese: Swap it for Swiss cheese or mozzarella if you prefer a different taste.
Mayonnaise: Substitute Greek yogurt or sour cream for a lighter alternative.
Spicy brown mustard or whole grain mustard can be used in place of Dijon mustard.
Thyme, fresh: Dried thyme (1/2 the amount) or fresh rosemary leaves can be substituted.

Pro Tips

1. Perfect Caramelization To caramelize onions efficiently, sprinkle a pinch of baking soda over them while cooking. This speeds up caramelization, helping achieve that rich, sweet flavor even faster.

2. Enhanced Flavor Instead of just using mayonnaise, create a quick aioli by mixing in a clove of minced garlic and a squeeze of lemon juice. This will add a subtle depth of flavor to the sliders.

3. Sealing in Juices Toast the bottom half of the buns lightly before adding toppings. This creates a barrier, preventing the bun from getting soggy from the sauces and beef juices.

4. Cheese Variation Mix cheeses for added flavor complexity. Consider using a combination of provolone with Swiss or mozzarella for a blend of creamy and sharp cheese profiles.

5. Crispy Top Tip For an extra crispy top, after removing the foil, brush the tops of the buns with a little more melted butter and sprinkle with sea salt or garlic powder before the final bake.