Preheat the oven to 350°F (176℃). Prep all ingredients per instructions above.
In a small bowl, combine salt, mustard, black pepper, garlic, onion powder, thyme, and rosemary. Then rub all over the roast covering well.
Place the roast in a roasting pan, fat side up, and insert a meat thermometer.
Roast for (about 13 minutes per pound) to your desired internal temperature (see below).
Transfer the roast to a cutting board, cover with foil, and let it stand for 15 minutes.
For merlot au jus, pour pan drippings into a measuring cup, skim off fat, and add beef broth, Merlot, and Worcestershire sauce. Heat and stir until bubbly. Optionally, thicken with water and cornstarch.
For horseradish cream, combine sour cream, mayonnaise, scallions, horseradish, mustard, and salt. Chill until serving.