Slow roasted beef tenderloin is an elegant, impressive main dish that’s surprisingly easy to prepare. With a tender (cut-with-a-fork) buttery texture, beef tenderloin is a mild cut of beef with minimal fat. And, when slow roasted, it’s evenly cooked and moist inside with a slightly crispy crust. I’ve been hosting dinner parties since I was 16 years old, and over the years I’ve perfected easy, foolproof dishes for elegant entertaining – and this recipe is a perfect example.

Slow Roasted Beef Tenderloin

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, I encourage you to figure out how to use it. Once I finally started to use mine, I never under or over-cooked a piece of meat again.

What You Need for Roast Beef Tenderloin

You only need 4 ingredients to slow roast a beef tenderloin:

  • Whole beef tenderloin
  • Olive oil
  • Kosher salt
  • Fresh ground pepper
  • Vegetable or other neutral, high heat oil (for searing)

You can amp up the flavor like the steak houses do by basting the cooked tenderloin with melted butter flavored with garlic and fresh herbs (like rosemary, tarragon or thyme). I prefer to keep the beef pure and serve my Horseradish Mustard Sauce on the side (see recipe inside recipe card below).

How to Slow Roast Beef Tenderloin in Oven

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!

Here’s a summary of the steps involved slow roasting a tenderloin:

  1. Prep oven.
    Preheat the oven to 275 degrees.
  2. Prep tenderloin.
    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. Sear.
    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. Roast.
    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. Cover and let rest.
    When meat reached desired temperature, remove it from the oven, cover loosely with foil and let rest at room temperature for at least 10 minutes before serving.
whole roasted beef tenderloin with a few slices in front and sauce on the side

How to Serve Roasted Beef Tenderloin

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.

Slow Roasted Tenderloin Storage

The tenderloin can be seared and roasted earlier in the day. I prefer to roast it so it’s done around 2 hours before serving. That way you can let it sit, covered, at room temperature. If you want to cook it earlier in the day (or the day before), once it’s cooked and cooled, wrap it in foil and refrigerate. Bring to room temperature before serving. You can warm it, wrapped in the foil in a 300 degree oven for around 10 to 15 minutes, but it may dry out a bit.

Oven Roasted Beef Tenderloin FAQs

Beef Tenderloin Temperature?

I recommend cooking beef tenderloin to 135 degrees for medium rare, up to 145 degrees for medium. Cooking it any longer can dry it out.

How long should I cook beef tenderloin?

Beef tenderloin should be cooked by temperature not by time. It’s best when cooked to 135 degrees for medium rare, up to 145 degrees for medium. Cooking it any longer can dry it out.

Should you sear beef tenderloin before roasting?

I like to sear my beef before roasting. Some chefs sear after – it’s somewhat personal preference. The most important step is to salt your meat before cooking!

Is beef tenderloin a good piece of meat?

Yes, beef tenderloin is an excellent cut of beef – and one of the most expensive. It’s tender and juicy, with little fat.

Is a beef tenderloin roast a filet mignon?

Filet mignon is part of a beef tenderloin. It is the most tender portion of the tenderloin, but with less beef flavor.

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whole roasted beef tenderloin with a few slices in front and sauce on the side

Slow Roasted Beef Tenderloin

Slow roasted beef tenderloin is an elegant, impressive main dish that’s surprisingly easy to prepare. With a tender (cut-with-a-fork) buttery texture, beef tenderloin is a mild cut of beef with minimal fat. And, when slow roasted, it’s evenly cooked and moist inside with a slightly crispy crust. It pairs well with this Horseradish Mustard Sauce on the side.

  • Yield: 6 servings 1x

Ingredients

Scale

Beef Tenderloin

  • 1 (2 1/2 to 3-pound) whole beef tenderloin, trimmed and tied*
  • Olive oil
  • Kosher salt
  • Fresh ground pepper
  • Vegetable or other neutral, high heat oil (for searing)

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

Instructions

Beef Tenderloin

  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.

Horseradish-Mustard Sauce

  1. In a medium mixing bowl, stir all ingredients together.
  2. Cover and refrigerate for at least 30 minutes to allow the flavors to blend. Season to taste with kosher salt before serving.

Notes

*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.

  • Author: By Lee Clayton Roper
  • Category: Beef, Entertaining, Gluten free
whole roasted beef tenderloin with a few slices in front and sauce on the side

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About the author

Hi, I'm Lee.

I am inspired by my mother, Sally’s, love of cooking and entertaining to gather friends and family together over great meals and conversation. In fact, I held my first dinner party at the age of 16. Throughout the years, I haves provided recipes, menu advice and cooking tips to friends seeking uncomplicated and delicious ideas for home entertaining.


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