Ingredients
Roast Beef Sandwich
- 2 ½ pounds beef top sirloin roast
- Olive oil, for rubbing
- Salt, about 2 teaspoons
- Black pepper, ½ to 1 teaspoon
- 2 teaspoons granulated onion
- 2 teaspoons granulated garlic
- 2 medium white onions, halved and sliced thinly (optional)
- 6 onion buns, toasted
- Prepared horseradish (optional spread for buns)
Creamy Cheddar Sauce
- ¾ ounce butter (about 1 ½ tablespoons)
- ¾ ounce flour (about 3 scant tablespoons)
- 1 ½ cups whole milk
- 2 cups shredded sharp cheddar cheese
- ¼ teaspoon granulated onion
- ¼ teaspoon ground mustard powder
- ¼ teaspoon paprika
- ¼ teaspoon (slightly heaping) salt
Instructions
- Prep the Ingredients: Gather all ingredients for the roast beef sandwich and creamy cheddar sauce, ensuring everything is ready and organized for cooking.
- Preheat and Prepare Oven: Preheat your oven to 325°F (163°C). Line a baking sheet with foil and place a wire rack over it to allow even roasting of the beef.
- Season the Beef: Rub the beef top sirloin roast all over with olive oil. Sprinkle about 2 teaspoons of salt, ½ to 1 teaspoon black pepper, 2 teaspoons granulated onion, and 2 teaspoons granulated garlic evenly on the meat, rubbing the seasonings in thoroughly.
- Roast the Beef: Place the seasoned beef on the wire rack. Insert a digital thermometer into the thickest part. Roast in the oven for approximately 1 hour and 15 minutes, or until the internal temperature reaches 125°F to 135°F (52°C to 57°C) for medium-rare to medium. Remove from oven and let rest, wrapped loosely, for about 15 minutes before slicing very thinly.
- Caramelize Onions (Optional): While the beef roasts, heat 3 to 4 tablespoons of olive oil in a skillet over medium-high heat. Add the thinly sliced onions with a pinch of salt and pepper. Sauté for 15 to 20 minutes, stirring occasionally, until the onions become deeply browned, jammy, and caramelized. Remove from heat and set aside.
- Prepare Cheddar Sauce: In a small pot over medium-low heat, melt 1 ½ tablespoons (¾ oz) butter. Sprinkle in 3 scant tablespoons (¾ oz) flour, stirring continuously for about 1 minute to form a roux. Gradually whisk in 1 ½ cups whole milk until smooth. Continue cooking and whisking frequently for 5 to 10 minutes until the sauce thickens and simmers gently.
- Add Cheese and Seasonings: Remove pot from heat. Whisk in 2 cups shredded sharp cheddar cheese in increments until fully melted and smooth. Stir in ¼ teaspoon granulated onion, ¼ teaspoon ground mustard powder, ¼ teaspoon paprika, and about ¼ teaspoon salt. Adjust seasoning to taste and keep sauce warm.
- Assemble the Sandwich: Take a toasted onion bun, spread prepared horseradish on top and bottom buns if desired. Place a generous layer of thinly sliced roast beef on the bottom bun. Spoon about ¼ cup of warm creamy cheddar sauce over the beef. Top with caramelized onions if using. Close the sandwich with the top bun and serve immediately.
Notes
- Use a digital instant-read thermometer to ensure perfectly cooked roast beef to preferred doneness.
- Caramelized onions add a sweet, savory depth but can be omitted if desired.
- Prepared horseradish adds a spicy kick and balances the richness of the cheddar sauce.
- Slice the beef as thinly as possible for the best sandwich texture.
- The cheddar sauce can be kept warm on very low heat or in a thermos if assembling sandwiches later.
- Onion buns toasted until golden enhance the sandwich with added crunch and flavor.
- Prep Time: 20 minutes
- Cook Time: 1 hour 35 minutes
- Category: Sandwiches
- Method: Roasting
- Cuisine: American
