Best Roast Beef Tenderloin (Filet Mignon) with Horseradish Sauce

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.

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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 – in fact, much easier than prime rib, another elegant and impressive main course for a dinner party. 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 if it’s done). 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 5 ingredients to slow roast a beef tenderloin:

• Whole beef tenderloin
• Olive oil
• Kosher salt
• Fresh ground black 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 am herb butter (melted butter flavored with garlic and fresh herbs like rosemary, tarragon or thyme). I often opt to simply serve my Horseradish Mustard Sauce on the side (see recipe inside recipe card below). Of course, for special occasions during the holiday season, you could do both!

How to Slow Roast Beef Tenderloin in Oven

In this recipe, I provide instructions for seasoning and searing the tenderloin before roasting. I believe this is the best way to cook 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 cast iron skillet (or other flat-bottomed skillet) 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 f for medium rare or 145 degrees f 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. Beef tenderloin is a moist tender cut of beef, which is why I recommend cooking it no more than medium (145 degrees).
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.

How to Serve Roasted Beef Tenderloin

You can serve this Slow Roasted Beef Tenderloin recipe 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.

Here are some other ideas for side dishes to serve alongside:

• Lemon Green Beans with Dijon Mustard
• Corn Pudding
• Oven Roasted Carrots
• Carrot Soufflé
• Aspargus Soufflé
• Asparagus Wrapped in Prosciutto
• Salad with Pear and Goat Cheese
• Arugula and Tomato Salad
• Spinach Salad with Lemon Dijon Dressing
• Anise Bread
• Twice Baked Potato Casserole
• Instant Pot Red Potatoes

For a more formal Christmas Eve (or other holiday) dinner, serve one of the above salads as a first course, then serve the tenderloin with two of the other side dishes.

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

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