Slow Roasted Beef Tenderloin with Horseradish-Mustard Sauce – an easy to prepare, make ahead, elegant and versatile main dish.


There is nothing more versatile – or more elegant – than beef tenderloin for a dinner party. It’s also very easy to prepare. You just have to purchase good quality beef and have an accurate meat thermometer (or, if you are like my brother Jim, that innate ability to poke a piece of meat and know how done it is!). If you have an oven with a built-in probe, figure out how to use it! Once I finally started to use mine, I never over-cooked a piece of meat again.

In this recipe, I provide instructions for seasoning and searing the tenderloin before roasting. This is my favorite method for cooking beef, because searing it over high heat layers in a deep, rich flavor. Make sure to salt the meat before searing it – this is the secret to searing’s effectiveness!

You can serve this Slow Roasted Beef Tenderloin with my Horseradish-Mustard Sauce on the side, as in the photo. I have also put slices on slider buns and served it sandwich-style – it’s flexible enough to be part of an elegant cocktail buffet or a casual picnic. You can also serve more than one sauce on the side – in addition to this horseradish sauce, I also like to serve it with the Argentine Chimichurri Sauce I serve with my Spicy Pork Chops.

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Slow-roasted-beef-tenderloin-with horseradish-mustard-sauce-recipe

Slow Roasted Beef Tenderloin with Horseradish-Mustard Sauce

  • Author: By Lee Clayton Roper
  • Yield: 6 servings 1x
  • Category: Beef, Entertaining, Gluten free



Beef Tenderloin:

  • 1 (2 1/2 to 3-pound) whole beef tenderloin, trimmed and tied*
  • Olive oil
  • Kosher salt
  • Fresh ground pepper

Horseradish-Mustard Sauce:

  • 3/4 cup mayonnaise
  • 1/4 cup prepared horseradish (or more to taste)
  • 2 tablespoons sour cream
  • 1 tablespoon whole grain or creole mustard
  • 2 teaspoons Dijon mustard
  • Kosher salt, to taste


  1. Preheat the oven to 275 degrees.
  2. Pat the tenderloin dry with paper towel. Brush all over lightly with olive oil. Season generously with salt and fresh ground pepper. Let sit at room temperature for 20 to 30 minutes.
  3. Coat a skillet (preferably cast iron) large enough to hold the tenderloin with vegetable oil and heat over high heat – or heat a grill to high. When hot, sear the outside of the tenderloin just until browned on all sides. Don’t turn too much!
  4. Place the seared tenderloin in a roasting pan or on a broiler rack and roast until the internal temperature reaches 135 degrees for medium rare or 145 degrees for medium – around 45 to 60 minutes. I recommend checking the temperature frequently, starting at around 30 minutes. the size and thickness of your tenderloin can change the cooking time significantly
  5. When meat reached desired temperature, remove it from the oven, cover with foil and let sit for at least 10 minutes before serving.
  6. For the horseradish-mustard sauce: in a medium mixing bowl, stir all ingredients together. Cover and refrigerate for at least 30 minutes to allow the flavors to blend. Season to taste with kosher salt before serving.


*Ask your butcher to trim and tie the tenderloin for you.

Make ahead: The sauce can be prepared, covered and stored in the refrigerator up to 2 days before serving. The tenderloin can be seared, roasted, cooled, covered, and refrigerated earlier in the day. Bring to room temperature before serving.

Lee Clayton Roper


I’m Lee Clayton Roper, and I’m passionate about making cooking and entertaining easy, elegant and fun. Here you’ll find scrumptious recipes, helpful tips and seasonal menus that will spark inspiration in your kitchen!
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