1. Make the Horseradish Sauce:

2. Combine 1 cup sour cream, ½ cup mayonnaise, 2 tablespoons horseradish, 1 teaspoon vinegar, and ½ teaspoon salt in a mixing bowl. Stir until smooth.

3. Cover and refrigerate for at least 1 hour before serving.

4.

5. Prepare Beef Tenderloin On Smoker:

6. Place the tenderloin on a sheet pan with a wire rack. Rub the entire surface with 1 to 2 tablespoons of oil.

7. Sprinkle 2 tablespoons of seasoning blend liberally over the entire tenderloin.

8. Place in the refrigerator uncovered for 12 hours or overnight (optional, but recommended).

9. Remove the tenderloin from the refrigerator 30 minutes before smoking.

10. Fold the thin tail end under and secure with kitchen twine. Continue tying the tenderloin at 2-inch intervals.

11. Preheat smoker to 225°F and add wood chips.

12. Insert a probe thermometer into the center of the thickest part of the tenderloin.

13. Place the tenderloin on the smoker grates and smoke for about 1 hour, or until the internal temperature reaches 115–120°F for medium-rare.

14. Preheat a cast-iron skillet over medium-high heat. Add 2 tablespoons of butter.

15. Place the smoked tenderloin in the skillet and sear for 60 to 90 seconds on each side until a deep golden-brown crust forms.

16. Transfer to a cutting board and let it rest for 15 minutes before slicing.

17. Remove the kitchen twine, slice into ½ to ¾-inch thick medallions, and serve with the chilled horseradish sauce.