3 1/2 – 4 pound beef tenderloin roast, trimmed
1 stick unsalted butter, softened but not melted
1 head of garlic
1 small shallot, minced
1 tablespoon Worcestershire sauce
1 teaspoon Dijon mustard
1 ½ tablespoons red wine reduction (1/3 cup red wine needed to create the reduction. Instructions below.)
2 tablespoons fresh rosemary, minced
1 tablespoon canola oil
1 ½ teaspoons salt
½ teaspoon fresh ground black pepper
Preheat the grill to around 400°F. Take an entire head of garlic and cut the top third completely off. Place the garlic on a piece of aluminum foil. Drizzle with extra-virgin olive oil and sprinkle with salt. Wrap tightly in foil and place over indirect heat on the grill for 35 to 40 minutes. Carefully remove, unwrap, and squeeze the softened cloves out of the bulb and into a bowl. Mash with a fork and set aside.
Meanwhile, to create the red wine reduction, in a small saucepan bring 1/3 cup red wine to a low simmer. Simmer uncovered until thickened and reduced to 2 tablespoons or so.
With paper towels, pat the tenderloin dry. Fold the tapered ends of the tenderloin under itself, then secure tightly with cooking twine. Continue to tightly tie the tenderloin in sections so it forms a uniform shape. This will guarantee even cooking.
Cream together the butter, roasted garlic, red wine reduction, Worcestershire sauce, shallot, rosemary, Dijon mustard, salt and pepper until well combined. Using cold, wet hands to keep the butter from sticking, pat the butter concoction all over the tenderloin. Cover the loin in plastic wrap and chill in the refrigerator for 1 hour or up to a day.
Let the tenderloin come to room temperature while you heat the grill to 250°F. Remove the tenderloin from the plastic wrap and carefully wrap it in aluminum foil, making sure the juices and melted butter will not leak out when rotating it while on the grill. Remember, you’re basically making a buttery, herbaceous flavor packet for the tenderloin to slow roast inside.
Place the tenderloin in the Char-Broil Roast and Grill Rib Rack on the center of your grill, and slow cook for 2 to 3 hours until the desired internal temperature has been reached. Flip the tenderloin every 30 minutes or so, for a flavorful butter-baste. Start checking at 2 hours, as ours was done at 2 hours and 20 minutes.
Remove at 125°F for rare or 130°F for medium rare. Let sit at room temperature for 10 minutes while you increase the heat on the grill to medium-high heat. Carefully remove the tenderloin from the foil, reserving all of the juices.
Sear the tenderloin on the grill until well-browned on all sides. Transfer it to a cutting board and allow to rest for 5 minutes. Slice into 1/2-inch slices and drizzle with reserved cooking juices.