Creamy Horseradish Roast Beef Burger

Imperial May 31, 2026May 31, 2026

Quick Recipe Version (TL;DR)

Yield: 4 burgers
Prep Time: 20 minutes
Cook Time: 50 minutes
Total Time: 1 hour 10 minutes

Quick Ingredients

For the onions: 2 large yellow onions, 1 tablespoon unsalted butter, 1 tablespoon olive oil, 1/4 teaspoon fine sea salt, 1 teaspoon brown sugar, 1 teaspoon balsamic vinegar
For the horseradish mayo: 1/3 cup mayonnaise, 2 tablespoons prepared horseradish, 1 teaspoon Dijon mustard, 1 teaspoon lemon juice, 1/4 teaspoon Worcestershire sauce, 1/8 teaspoon fine sea salt, 1/8 teaspoon black pepper
For the patties: 1 1/2 pounds 80/20 ground beef, 1 tablespoon Worcestershire sauce, 2 teaspoons Dijon mustard, 1 teaspoon low-sodium beef bouillon powder, 1 teaspoon fine sea salt, 1 teaspoon onion powder, 3/4 teaspoon garlic powder, 1/2 teaspoon dried thyme, 1/2 teaspoon black pepper, 1/4 teaspoon smoked paprika
For assembly: 4 brioche or potato buns, 1 tablespoon softened unsalted butter, 4 slices Swiss cheese, caramelized onions, horseradish mayo

Do This

1. Stir together the horseradish mayo ingredients and refrigerate for at least 15 minutes.
2. Cook sliced onions with butter, olive oil, and salt over medium heat for 8 minutes, then reduce heat and caramelize for 25 to 30 minutes more.
3. Mix the roast beef-style seasonings into the ground beef gently, then form 4 patties with a shallow dimple in the center.
4. Butter and toast the buns, cut side down, for 1 to 2 minutes until golden.
5. Cook patties in a hot skillet or on a 400°F griddle for 3 to 4 minutes per side, topping with Swiss during the final 1 to 2 minutes.
6. Build each burger with horseradish mayo, a Swiss-topped patty, caramelized onions, and the top bun. Serve hot.

Why You’ll Love This Recipe

It tastes like a steakhouse sandwich in burger form. Savory roast beef-style seasoning, creamy horseradish mayo, Swiss cheese, and sweet onions bring the classic open-faced roast beef sandwich vibe.
The sauce is simple but bold. Prepared horseradish adds just enough heat without overpowering the burger.
Caramelized onions do the heavy lifting. They add deep sweetness that balances the sharp sauce and rich beef.
It is special but still weeknight-friendly. The onions take a little time, but the steps are straightforward and easy to manage at home.

Grocery List

Produce: 2 large yellow onions, 1 lemon
Dairy: Swiss cheese slices, unsalted butter
Meat: 1 1/2 pounds 80/20 ground beef
Bakery: 4 brioche or potato burger buns
Pantry: Mayonnaise, prepared horseradish, Dijon mustard, Worcestershire sauce, low-sodium beef bouillon powder, olive oil, brown sugar, balsamic vinegar, fine sea salt, black pepper, onion powder, garlic powder, dried thyme, smoked paprika

Full Ingredients

For the Creamy Horseradish Mayo

1/3 cup mayonnaise
2 tablespoons prepared horseradish, stirred well and lightly drained if watery
1 teaspoon Dijon mustard
1 teaspoon fresh lemon juice
1/4 teaspoon Worcestershire sauce
1/8 teaspoon fine sea salt
1/8 teaspoon freshly ground black pepper

For the Caramelized Onions

2 large yellow onions, about 1 pound total, thinly sliced
1 tablespoon unsalted butter
1 tablespoon olive oil
1/4 teaspoon fine sea salt
1 teaspoon packed light brown sugar
1 teaspoon balsamic vinegar
2 to 4 tablespoons water, as needed to prevent scorching

For the Roast Beef-Seasoned Patties

1 1/2 pounds 80/20 ground beef, cold
1 tablespoon Worcestershire sauce
2 teaspoons Dijon mustard
1 teaspoon low-sodium beef bouillon powder, finely crushed if granulated
1 teaspoon fine sea salt
1 teaspoon onion powder
3/4 teaspoon garlic powder
1/2 teaspoon dried thyme
1/2 teaspoon freshly ground black pepper
1/4 teaspoon smoked paprika
2 teaspoons neutral oil, such as avocado or canola oil, for the skillet

For Assembly

4 brioche or potato burger buns, split
1 tablespoon unsalted butter, softened
4 slices Swiss cheese, about 1 ounce each
Prepared horseradish mayo
Prepared caramelized onions

Creamy Horseradish Roast Beef Burger – Closeup

Step-by-Step Instructions

Step 1: Make the horseradish mayo

In a small bowl, stir together the mayonnaise, prepared horseradish, Dijon mustard, lemon juice, Worcestershire sauce, fine sea salt, and black pepper until smooth and creamy. Taste it: if you love a sharper horseradish bite, you can add 1 extra teaspoon of prepared horseradish, but the base recipe is balanced for a bold yet family-friendly sauce.

Cover the bowl and refrigerate the sauce for at least 15 minutes while you make the onions. This short rest helps the flavors blend and gives the sauce a better sandwich-shop style taste.

Step 2: Caramelize the onions

Place a large skillet over medium heat. Add 1 tablespoon unsalted butter and 1 tablespoon olive oil. Once the butter melts, add the thinly sliced onions and 1/4 teaspoon fine sea salt. Cook for 8 minutes, stirring often, until the onions soften and begin to turn pale golden around the edges.

Reduce the heat to medium-low. Continue cooking for 25 to 30 minutes, stirring every 3 to 4 minutes. If the onions begin sticking or browning too quickly, add 1 tablespoon water at a time and scrape up the browned bits from the pan. When the onions are soft, jammy, and deep golden brown, stir in 1 teaspoon brown sugar and 1 teaspoon balsamic vinegar. Cook for 2 more minutes, then remove from the heat. The total onion cooking time should be about 35 to 40 minutes.

Step 3: Mix the roast beef-style seasoning

In a large bowl, combine the Worcestershire sauce, Dijon mustard, low-sodium beef bouillon powder, fine sea salt, onion powder, garlic powder, dried thyme, black pepper, and smoked paprika. Stir until the seasonings form a loose, savory paste. This seasoning blend gives the ground beef the cozy, roasted flavor you expect from a hot roast beef sandwich.

Add the cold ground beef to the bowl. Using clean hands or a fork, gently fold the seasoning into the beef just until evenly distributed, about 8 to 10 gentle turns. Avoid squeezing or kneading the meat, which can make the burgers dense.

Step 4: Shape the patties

Divide the seasoned beef into 4 equal portions, about 6 ounces each. Shape each portion into a patty about 4 1/2 inches wide and 3/4 inch thick. Press a shallow dimple into the center of each patty with your thumb; this helps the burgers cook evenly and reduces puffing in the middle.

Place the patties on a plate and let them rest at room temperature for 10 minutes while you toast the buns and heat the skillet. Do not leave the raw patties out for more than 30 minutes.

Step 5: Toast the buns

Spread the cut sides of the buns with 1 tablespoon softened unsalted butter, dividing it evenly. Heat a large skillet or griddle over medium heat. Place the buns cut side down and toast for 1 to 2 minutes, until golden and lightly crisp. Transfer the buns to a plate.

Toasting the buns adds flavor and gives the horseradish mayo a better surface to cling to, so the burger stays rich and saucy without becoming soggy too quickly.

Step 6: Cook the patties and melt the Swiss

Wipe the skillet clean if there are any burned crumbs from the buns. Add 2 teaspoons neutral oil and heat the skillet over medium-high heat for about 3 minutes, or set an electric griddle to 400°F. The pan is ready when a drop of water sizzles immediately on contact.

Add the patties to the hot skillet, leaving space between them. Cook for 3 to 4 minutes on the first side without pressing down. Flip the patties and cook for 2 minutes more. Place 1 slice of Swiss cheese on each patty, cover the pan with a lid, and cook for 1 to 2 minutes longer, until the cheese softens and the burgers reach an internal temperature of 160°F on an instant-read thermometer.

Step 7: Assemble the burgers

Spread about 1 tablespoon of horseradish mayo on the bottom half of each toasted bun. Add a Swiss-topped roast beef-seasoned patty, then spoon a generous layer of caramelized onions over the cheese. Spread another 1 to 2 teaspoons horseradish mayo on the top bun, then close the burger.

Let the assembled burgers rest for 2 minutes before serving. This gives the cheese and sauce a moment to settle into the onions and patty, creating that creamy, savory roast beef sandwich effect in every bite.

Pro Tips

Use 80/20 beef for the best texture. Leaner beef works, but 80/20 stays juicier and gives the burger a richer roast beef-style flavor.
Do not rush the onions. Medium-low heat is the secret. If they brown too fast, use a splash of water and keep going.
Do not press the patties while cooking. Pressing squeezes out moisture and can make the burgers dry.
Check the internal temperature. Ground beef should reach 160°F for safe serving.
Balance the horseradish to your taste. Prepared horseradish varies in strength, so taste the sauce before serving and adjust with a little more mayo or lemon juice if needed.

Variations

Open-faced roast beef burger: Serve each patty on one toasted bun half with Swiss, caramelized onions, and extra horseradish mayo spooned over the top. Skip the top bun for a more direct nod to an open-faced roast beef sandwich.
Mushroom Swiss version: Add 8 ounces sliced cremini mushrooms to the skillet after the onions are done. Cook for 7 to 9 minutes, then pile them onto the burgers with the caramelized onions.
Extra sharp horseradish burger: Increase the prepared horseradish to 3 tablespoons and add 1/2 teaspoon extra lemon juice to the mayo.

Storage & Make-Ahead

The horseradish mayo can be made up to 5 days ahead and stored in an airtight container in the refrigerator. The caramelized onions can be made up to 4 days ahead; rewarm them in a skillet over low heat for 5 to 7 minutes, adding 1 teaspoon water if needed. For the best burger texture, shape and cook the patties the same day you mix them. Cooked patties can be refrigerated for 3 to 4 days and reheated in a 300°F oven for 8 to 10 minutes, or in a covered skillet over low heat for 5 to 6 minutes. Assemble the burgers just before serving so the buns stay toasted and the sauce stays creamy.

Nutrition (per serving)