For pesto, in blender or food processor combine cilantro, walnuts, oil, lime juice, garlic, and salt. Cover and blend or process until nearly smooth. Set aside.
Split each turkey tenderloin in half horizontally. Sprinkle lightly with salt and black pepper.
Place turkey on the rack of an uncovered grill directly over medium coals. Grill for 7 minutes. Turn turkey; brush lightly with pesto. Grill for 5 to 8 minutes more or until turkey is tender and no longer pink (170 degree F). Serve turkey with remaining pesto. If desired, serve with lime wedges to squeeze over turkey. Makes 8 servings.