Preparation

• Position a rack in the center of the oven, and heat the oven to 325°F. Prepare 3 rectangles of foil large enough to wrap the tenderloins individually.
• In a small bowl, combine 2 Tbs. salt, 11/2 Tbs. pepper, the rosemary, and turmeric. Pat the tenderloins dry, and place on a large rimmed baking sheet. Rub the meat all over with the spice mixture, pressing into the meat to ensure that it adheres. Finely chop the parsley and sage, and combine with the butter and garlic in a medium bowl. Set aside.
• Heat the coconut oil in a large cast-iron skillet over medium heat until shimmering. Sear the tenderloins one at time, until light golden-brown, turning to brown all over, about 8 minutes total. Wipe out the pan with paper towels between batches, and add more oil as necessary. Lower the heat if the pan gets too hot. Place each tenderloin on a sheet of foil. Evenly distribute the herb-garlic butter over the top of each tenderloin. Fold the short sides of the foil over the tenderloins, then fold the longer sides upward to meet the short sides. Fold the foil edges together to loosely enclose the meat. (The tenderloins can be made to this point up to 1 day ahead and refrigerated. Bring to room temperature before continuing.) Place the wrapped tenderloins on a large rimmed baking sheet, and roast until an instant-read thermometer inserted into the thickest part of the meat registers 145°F, about 25 minutes. Remove from the oven, and let rest for 15 minutes.
• Meanwhile, in a small bowl combine the basil, mint, olive oil, vinegar, lemon zest and juice, and 1/2 tsp. each salt and pepper. Stir until well combined. Slice the meat, and serve drizzled with the herb sauce.