Pork tenderloins typically come with two tenderloins in each package. Make a double batch of herb rub if cooking both tenderloins for a bigger dinner or meal prep through the week.
Preheat the oven to 425°F.
Trim any extra fat from the pork tenderloin. In a small bowl mix together the herbs, garlic, and salt and pepper. Rub all over the pork, pressing the mixture into the meat so it adheres well.
Heat a large cast-iron skillet on medium-high heat with the oil and place the pork tenderloin in the pan. Cook for 10 minutes, turning every 3 minutes on each side until lightly browned. Transfer the pork to the oven and cook for 10 minutes. Add the lemon slices to the skillet with the pork and cook for 10 more minutes or until cooked through and the internal temperature of the pork is 145°F. Remove from the oven, cover with foil, and let stand for 5 minutes. Slice and serve with sautéed spinach and garlic or your favorite side dish.