Preheat the Traeger with the lid closed to 180°F; use Super Smoke if available.

In a small bowl, combine the rosemary, thyme, porcini powder, and zest. Season with a few good pinches salt and pepper and mix well. Lightly coat the tenderloin all over with olive oil. Coat the tenderloin all over with the porcini mixture.

Insert leave-in meat thermometer or a wireless one like MEATER® into the middle of the tenderloin. Place the meat directly on the grill grate and smoke for 1 hour.

While the tenderloin is smoking, make the red wine mushroom sauce. Heat a deep pan over medium-heat and add the olive oil. When the oil is shimmering, add the mushrooms and cook, stirring often, until browned all over, 8 to 10 minutes. Season with a pinch of salt, then remove the mushrooms from the pan and set aside.

Add 2 tablespoons of the butter to the pan, then add the shallots and a pinch of salt and cook until starting to soften, 3 to 4 minutes. Stir in the garlic and porcini powder, cook for 45 seconds, then add the red wine, bring to a simmer, and reduce by half. Add the stock and cook to reduce slightly.

Return the mushrooms to the pan and let bubble away until thickened, 10 to 15 minutes (it should be thick enough to coat the back of a wooden spoon). Turn off the heat, then add the remaining butter and stir until the sauce is creamy, thickened, and the butter is emulsified. Season with more salt and pepper to taste.

Remove the smoked tenderloin from the grill and heat the grill to 400°F. Return the tenderloin to the grate and cook until it has an internal temperature of 125°F for medium rare, about 20 minutes.

Transfer the tenderloin to a cutting board and let rest for 15 minutes.

Slice the tenderloin and serve with a generous amount of sauce and a sprinkling of fresh chives. Enjoy!