Roast Beef Burger with Horseradish Cream

A roast beef burger layers tender slices of cooked beef on a toasted bun with sharp horseradish cream and crisp, savory toppings. It is a quick way to turn deli roast beef or leftovers into a substantial hot sandwich without cooking a raw burger patty.

Ingredients

4 burger buns, about 2 oz (55 g) each
1 lb (450 g) thinly sliced cooked roast beef
1 tablespoon (15 ml) olive oil
1 small yellow onion, about 5 oz (140 g), thinly sliced
1/2 cup (120 ml) low-sodium beef broth
1/2 teaspoon (2.5 ml) Worcestershire sauce
1/4 teaspoon (1 g) kosher salt, plus more to taste
1/4 teaspoon (0.5 g) freshly ground black pepper
4 slices (about 3 oz / 85 g total) provolone cheese
1/3 cup (80 g) sour cream
1 tablespoon (15 g) prepared horseradish, drained if very wet
1 teaspoon (5 ml) Dijon mustard
1 cup (30 g) loosely packed arugula
2 teaspoons (10 g) unsalted butter, softened, for toasting the buns

Instructions

Stir together the sour cream, horseradish, and Dijon mustard in a small bowl. Taste and add a little more horseradish if you want a stronger bite. Cover and refrigerate while you prepare the beef.
Heat the olive oil in a large skillet over medium heat. Add the sliced onion and cook for 6–8 minutes, stirring occasionally, until soft and golden at the edges. If it begins to brown too quickly, lower the heat; the onion should be tender rather than scorched.
Pour in the beef broth and Worcestershire sauce, then stir in the salt and pepper. Bring the liquid to a gentle simmer. Add the cooked roast beef in loose slices and turn it gently in the broth just until hot, about 2–3 minutes. Avoid a hard boil or prolonged cooking, which can make thin beef tough. Since this recipe uses cooked beef, reheating it to 165°F (74°C) is the USDA FSIS safe temperature for leftovers; check the center of the meat with a food thermometer.
While the beef warms, split the buns and spread the cut sides with softened butter. Toast them cut-side down in a clean skillet over medium heat for 1–2 minutes, or until lightly browned. You can also toast them under a broiler, watching closely so they do not burn.
Use tongs to divide the warm beef and onions among the bun bottoms, letting excess broth drip back into the skillet so the bread does not become soggy. Top each portion with a slice of provolone. Cover the skillet briefly or place the assembled open buns under the broiler for about 30–60 seconds, just until the cheese melts. Keep the buns a few inches from the heating element and watch continuously.
Spread horseradish cream on the bun tops. Add arugula over the melted cheese, close the burgers, and serve promptly while the beef and cheese are warm.

Tips

Use thin slices: Thinly sliced roast beef heats quickly and stays more tender. If slicing leftovers yourself, chill the roast first and cut across the grain with a sharp knife.
Keep the broth gentle: The skillet liquid is for warming and flavor, not boiling the beef. Lift the meat out with tongs rather than piling broth onto the buns.
Adjust the sauce: Prepared horseradish varies in heat. Start with one tablespoon, taste, and add more gradually. If you do not have sour cream, use plain Greek yogurt; the sauce will taste tangier and may be thicker.
Choose cheese to suit: Swiss or mild cheddar can replace provolone. Stronger cheeses will bring a more pronounced flavor and can compete with the horseradish.

Serving Suggestions

Serve the burgers immediately with oven fries, potato wedges, or a simple green salad. Pickles, crisp coleslaw, or lightly dressed sliced tomatoes make refreshing sides alongside the rich beef and creamy sauce. For an easier meal, offer extra horseradish cream and a small bowl of the warm broth for dipping; keep the broth separate until serving so the buns stay intact.

Variations

Make it a French dip-style burger: Skip the arugula and serve extra warm beef broth in small cups for dipping. Use sturdy buns, and drain the beef well before assembling.

Add mushrooms: Cook 6 oz (170 g) sliced mushrooms with the onions, allowing their moisture to evaporate before adding broth. The topping will be earthier and more substantial.

Try a spicy version: Stir 1–2 teaspoons (5–10 ml) hot sauce into the horseradish cream, or add sliced pickled jalapeños to each burger. Taste before adding more, since both the horseradish and peppers can be potent.

Use barbecue flavors: Replace the horseradish cream with 1/4 cup (60 g) barbecue sauce mixed with 2 tablespoons (30 g) mayonnaise. This makes a sweeter, less sharp burger; omit the Dijon from the original sauce.

Storage and Reheating

For best texture, store the beef, broth, sauce, greens, and buns separately. Refrigerate cooked beef and onions within 2 hours in a covered container; they keep for 3–4 days at 40°F (4°C) or colder. Refrigerate the horseradish cream separately and use it within 3–4 days, following the sour cream’s package guidance. Toasted or assembled burgers soften, so assemble only what you plan to eat.

Reheat the beef and onions with a splash of broth in a covered skillet over medium-low heat, stirring until steaming hot and at least 165°F (74°C) throughout, as measured with a food thermometer. Reheat only the portion you need. Warm buns separately and assemble just before serving. Discard perishable food left at room temperature for more than 2 hours, or more than 1 hour when the temperature is above 90°F (32°C).

Frequently Asked Questions

Can I use leftover roast beef?
Yes. Refrigerated leftovers work well when they have been stored safely and are still within 3–4 days. Slice them thinly across the grain, then warm them gently with the broth and onions to 165°F (74°C).

Can I make these burgers with deli roast beef?
Yes. Choose plain or lightly seasoned roast beef rather than a heavily smoked variety, which can overpower the sauce. Deli slices are usually very thin, so add them near the end and heat only until warmed through to avoid a dry, chewy texture.

How do I stop the bun from getting soggy?
Toast the cut sides, drain excess broth from the beef, and spread sauce on the top bun rather than the bottom. Assemble just before eating, especially if you are using extra broth for dipping.

Is this the same as a raw beef burger?
No. This recipe uses already-cooked roast beef and does not shape or cook ground beef patties. If you adapt it using ground beef, cook the patties to the USDA FSIS safe minimum internal temperature of 160°F (71°C), measured with a food thermometer.

Can I prepare any part ahead?
Make the horseradish cream up to a day ahead and keep it covered in the refrigerator. You can slice the onion ahead too, but cook and reheat the beef close to serving time for the best texture.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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