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This Slow Roasted Beef Tenderloin uses the reverse sear technique to deliver a buttery soft texture on the inside with a delicious browned crust on the outside. This Beef tenderloin recipe with garlic herb butter is perfect for a special holiday dinner when you really want to impress!

Slow Roasted Beef tenderloin garnished with fresh herbs on a white platter.

For a big holiday dinner, there is nothing better than a big juicy roast. I normally go for my popular Slow Roasted Prime Rib recipe, but a Beef Tenderloin is also such a nice special occasion main course. This is a very expensive piece of meat, and it yields the most tender bite you have ever had.

What is Beef Tenderloin

Beef tenderloin is one of the most sough after and tender cuts of beef. Filet Mignon comes from the tenderloin, more specifically from the tip end of the tenderloin. This is a muscle that is not used much, which is why it is so buttery soft. It also doesn’t have much fat, which can make it a bit of a challenging cut. Although it is delicious, being lean makes it easier to overcook and it can sometimes use some added fat and flavor. This is why we add a garlic herb butter during and after our cooking process, to really enhance this already delicious cut of beef.

Uncooked Beef Tenderloin ties with twine and sitting on a cooling rack over a sheet pan lined with foil.

How to make the best slow roasted beef tenderloin

Scroll down for the full recipe, but here is an overview of how to make beef tenderloin.

You may buy something called a chateaubriand, which is essentially the center cut of the tenderloin, and the most uniform in size. Or you may buy a whole tenderloin, either way, you will want to make your roast as evenly sized as possible. You may cut the pointed ends and the “head’ off of the meat to use in another application, or leave them on and tuck them under to make a uniform sized roast.

Use kitchen twine to tie the roast so it is uniform in thickness and size. Then season very liberally with kosher salt. If possible, do this the day before cooking and let the roast stand in the refrigerator overnight for the best browning. Otherwise, do this one hour before cooking, and allow it to sit out at room temperature for one hour before cooking.

We will use the “reverse sear” method here for our slow roasted Beef tenderloin. This will allow the roast to cook evenly throughout while still achieving that beautiful browned crust on the outside. Reverse sear just means that instead of searing the meat BEFORE we cook it, we will sear it after.

Before cooking, season with pepper and rub with softened butter.

Roast at 300 degrees until the internal temperature reaches 120 degrees (for medium rare, see temperatures chart below). Remove from the oven 5-10 degrees BEFORE it reaches your desired final internal temperature.

Heat 1 tablespoon of vegetable oil – I like avocado oil for this because it has a very high smoke point – in a cast iron skillet or Dutch oven. Sear for 1-2 minutes per side, until there is a nice brown crust on the outside.

Rub with garlic herb butter and allow to rest for 15 minutes before carving.

Uncooked beef tenderloin ties with kitchen twine and rubbed with butter, as well as ties with twine. Sitting on a cooling rack over a baking sheet that is lined with foil.

How do I know when a beef tenderloin is done?

There is only ONE way to know that your roast has reached the right temperature, and that is with an instant read thermometer. Beef Tenderloin is an expensive cut of meat. Protect your investment by buying an inexpensive meat thermometer. Once you start using one, you will use it all the time!

I absolutely love our Thermapen and we use this Thermoworks BBQ Alarm to let us know exactly when the meat has reached the right temperature. However, if you want to start out with a less expensive option, this thermometer is very highly rated on amazon, has tons of great reviews and is under $20! And THIS highly rated wireless digital thermometer is a lower cost option that allows you to keep the probe in the meat while it is cooking, so you know exactly when it is done.

A cooked beef tenderloin before searing, on a rack over a sheet pan.

What should the internal temperature be for Beef Tenderloin?

You should take the roast out of the oven 5-10 degrees BEFORE it reaches your desired temperature. The roast will continue to cook after removing it from the oven due to heat carryover.

Beef Tenderloin temperature chart – when to take the roast out of the oven.

Rare – take out of the oven at 115 degrees
Medium Rare – take out of the oven at 120 degrees
Medium – Take out of the oven at 125 degrees
Medium Well – Take out of the oven at 130 degrees
Well Done – Take out of the oven at 140 degrees (Not recommended)

A cooked beef tenderloin that has been cut in half, topped with herb butter.

What temperature should I cook Beef Tenderloin at?

For this Slow Roasted Beef Tenderloin we cook the roast at 300 degrees F. If you have a convection oven, use 275 degrees F.

A beef tenderloin roast and some fresh green herbs on a white platter.

How much Slow Roasted Beef Tenderloin do I need per person?

For a beef tenderloin, plan on about 8 ounces per person. This is the weight before cooking. So for 4 people, you would want about 2 pounds of meat before cooking.

What to Serve with Slow Roasted Beef Tenderloin

The best sides to go with your beef tenderloin!