Warm Up Your Smoker: Begin by preheating your smoker to a consistent 250°F. For that classic festive aroma, apple wood pellets or chips are an excellent choice for a mild, fruity smoke.
Season the Roast: In a small bowl, thoroughly combine the sea salt, fresh cracked black pepper, dried parsley, and garlic powder. Drizzle the trimmed beef tenderloin with olive oil, then generously rub the seasoning mixture all over the meat, ensuring an even coating on every side.
Optional: Truss for Evenness: For the most uniform cooking and a beautifully rounded roast, you can gently tie the tenderloin with butcher’s twine at approximately 1-inch intervals. This simple step helps maintain a consistent thickness, preventing the ends from cooking faster than the middle.
Smoke to Perfection: Carefully place your seasoned tenderloin directly onto the smoker rack, positioned away from direct heat. Let it smoke for about 1 hour at 250°F, until its internal temperature reaches 110°F. Always use a reliable meat thermometer inserted into the thickest part for precise readings.
Achieve a Beautiful Sear: While the tenderloin is smoking, preheat a separate grill (charcoal or gas) to a high temperature, 500°F or more. Once the tenderloin reaches 110°F, gently transfer it to the hot grill. Sear each side for a total of about 5 minutes, turning frequently to develop a delicious, crusty exterior. Monitor the internal temperature closely, aiming for 120-125°F. (If a grill isn't available, you can achieve a fantastic sear in a smoking hot cast-iron pan on your stovetop or under your oven’s broiler.)
Rest and Serve: This vital step locks in all the juicy goodness! Remove the seared tenderloin from the heat and let it rest, uncovered, on a cutting board for 10 minutes. This allows the internal temperature to rise slightly and the juices to redistribute, ensuring every slice is incredibly moist and flavorful. (If you used twine, carefully remove it now.) Slice into generous 1-inch thick pieces and serve immediately with your favorite healthy holiday side dishes. Enjoy your perfectly cooked, lean, and festive feast!