French Onion Sliders are full of roast beef, swiss cheese, Dijon mustard, caramelized onions, and the flavor of France, with a buttery toasted bun. These sliders are perfect for any family celebration!
French Onion Sliders are easy to make and are packed with flavor. The caramelized onions steal the show. The seasoning used on the onions is Herbes de Provence, a mixture of dried herbs typical of the Provence region of southeastern France: savory, marjoram, rosemary, thyme, and oregano. Definitely a flavor that takes these sliders to a new level!
French Onion Sliders are small bites of goodness, perfect for when the family gets together.
The Secret Ingredients of the French Onion Sliders:
- Caramelized Onions made with unsalted butter, a yellow onion, Herbes de Provence, and water—the secret ingredient that helps the onions brown easier.
- The secret sauce that bakes onto the tops of the sliders is made of melted butter, Worcestershire sauce, mayonnaise, Dijon mustard, and minced garlic. When baked, this sauce creates the taste of buttery goodness in each slider. You don’t want to live without it!
- The secret to quick and easy sliders is King Hawaiian Sweet Rolls. They are the perfect slider size and they come packages together as a set of rolls—connected together. It’s easy to slice them in half all at once and lift off the tops as a whole unit.
- The secret inside the French Onion Sliders is not just the caramelized onions, combined with the roast beef and Swiss cheese, it’s the Dijon mustard spread on the bottom bun of each slider.
- A secret garnish for the tops of the French Onion Sliders is toasted sesame seeds and freeze-dried parsley. Sprinkle each of these on the sliders immediately after brushing the topper sauce on the buns. These two garnishes add color, texture, and flavor to the sliders.
How to Make French Onion Sliders:
Caramelized Onions:
Caramelized onions take patience. Often, we think of caramelized onions as tenderized onions and stop there. But to truly caramelize onions over medium-heat, you pass the tender onion stage and keep cooking, It takes about 20 minutes to reach caramelization. The onions become a darker brown and almost mushy in texture and the flavor intensifies when you reach that stage. Don’t forget to add the Herbes de Provence seasoning when you start to caramelize these onions.
The Sliders:
- Mix together the ingredients of the topper sauce and set aside.
- Preheat oven to 350° F. Spray 9×13 baking sheet with non-stick spray.
- Slice the slider buns in half, lift off the tops, and set aside. Place slider bottoms into a 9×13 baking sheet.
- Spread an even layer of Dijon mustard on the bottom half of each bun. Top with a layer of deli roast beef and a slice of Swiss cheese. Then, top with caramelized onions. Return tops of slider buns to the sandwich.
- With a pastry brush, spread topper sauce over the tops of the buns until the sauce is gone. Immediately sprinkle with sesame seeds and parsley.
- Loosely cover with foil. Bake at 350° F for 20-30 minutes, or until the cheese is melty. Remove foil and bake for another 5 minutes or until golden brown.
Au Jus Sauce:
The sauce is easy to make on the stovetop or the microwave. It’s definitely an optional sauce, especially if these sliders are going on a picnic. But the sauce is delicious with these French Onion Sliders.
With Memorial Day and summer celebrations right around the corner, enjoy making these French Onion Sliders to share with friends and family.
–Kim
French Onion Sliders
Equipment
- 1 9×13 baking sheet
Ingredients
Caramelized Onions:
- 2 Tablespoons unsalted butter
- 1 medium yellow onion thinly sliced
- 1 Tablespoon Herbes de Provence
- 1 Tablespoon water
- Salt and Pepper to taste
Topper Sauce:
- 5 Tablespoons unsalted butter melted
- 1 teaspoon Worcestershire sauce
- 2 Tablespoons mayonnaise
- 1 teaspoon Dijon mustard
- 1 clove minced garlic
The Sliders:
- 20 Hawaiian slider buns
- 6 Tablespoons Dijon mustard
- 1 pound deli roast beef
- 20 2×2 slices Swiss cheese
Garnish:
- 1 Tablespoon toasted sesame seeds
- 1 Tablespoon freeze-dried parsley
Au Jus Sauce:
- 1 Tablespoon unsalted butter
- 1 clove minced garlic
- 1 cup beef broth
- 1 Tablespoon Worcestershire sauce
- 1 Tablespoon dried parsley
- salt and pepper to taste
Instructions
Caramelized Onions:
- In a large skillet and over medium-high heat, melt butter. Add onion and Herbes de Provence, water, salt and pepper.
- Stirring occasionally, cook onions until they are tender and soft and becoming golden brown.
- Then continue to cook until they are caramelized, about 20 minutes. Remove from heat.
Topper Sauce:
- In a small microwave safe bowl, melt 5 Tablespoons butter.
- Add Worcestershire sauce, mayonnaise, Dijon mustard, and garlic. Mix well and set aside.
- If sauce thickens, microwave for 10 seconds to re-melt butter.
The Sliders:
- Preheat oven to 350° F. Spray 9×13 baking sheet with non-stick spray.
- As a group, slice Hawaiian slider buns in half, lift off the tops (as a group), and set aside. Place slider bottoms (as a group) into a 9×13 baking sheet.
- Spread an even layer of Dijon mustard on the bottom half of each bun.
- Top with a layer of deli roast beef and a slice of Swiss cheese. Top with caramelized onions.
- Return tops of slider buns to the sandwich.
- With a pastry brush, spread sauce over the tops of the buns until the sauce is gone. Immediately sprinkle with sesame seeds and parsley.
- Loosely cover with foil. Bake at 350° F for 20-30 minutes, or until the cheese is melty.
- Remove foil and bake for another 5 minutes or until golden brown.
Au Jus Sauce:
- In a small saucepan, melt butter. Add minced garlic and toast for 1 minute, or until golden. It burns easily, so watch closely.
- Add beef broth, Worcestershire sauce, and parsley. Continue to cook until warm.
- Add salt and pepper to taste. Serve warm.
Notes
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