Preheat oven to 450 degrees.
In a small bowl, combine the garlic, rosemary, lemon juice, salt, and pepper. Coat the tenderloin with the spice mixture.
In a large skillet with an oven-proof handle over medium heat, heat the oil.
Brown the tenderloin in the skillet, turning to brown all sides, about 8 to 10 minutes, or until internal temperature reaches 155 degrees (160 degrees after standing).
Transfer skillet to oven and roast the tenderloin for 10 minutes. Remove roast to a platter to keep warm.
Return the skillet to the stove, over high heat, and stir in the broth and the vinegar, scraping up any browned bits. Let the liquid reduce by half, and then whisk in the butter.
Slice the tenderloin in ½-inch slices and serve with the pan sauce.