The Day Prior to Cooking (*optional but recommended)

Cut the tenderloin in half to make two pieces. Tuck the long end under and use butcher's twine to tie the tenderloin.
Season all over with salt and pepper and leave in fridge, uncovered on a wire rack overnight, or at least 10 hours. Dehydrating the outside will create the best crust when seared. (I do this to all of my meat prior to searing!)

Day of Cooking

Remove tenderloin from fridge and set on counter to come to room temperature.
Preheat oven to 425 degrees F. Place oil in a large cast-iron skillet and heat over medium-high heat. Sear the tenderloin on all sides, about 3 to 5 minutes per side, creating a nice golden-brown crust.
Meanwhile combine the softened butter, garlic, honey, horseradish/mustard and herbs in a small dish and mix.
Place the meat back onto the wire rack/roaster. Using a pastry brush, spread the seared tenderloin with the butter mixture and then insert a probe thermometer (or you can use an instant read later).
Roast until desired internal temperature is reached, about 20 to 25 minutes. *See notes for temperatures.
Remove tenderloin from oven and transfer to a cutting board. Let rest for 15 to 20 minutes to allow the juices to redistribute before slicing into 1" slices. Enjoy!

Roasted Beef Tenderloin with Horseradish and Thyme