- Preheat oven to 400 degrees F.
- Tie kitchen string around tenderloin in three places so it doesn’t flatten while roasting.
- Rub the tenderloin with oil; pat on salt and pepper. Place in a large roasting pan.
- Roast until a thermometer inserted into the thickest part of the tenderloin registers 140 degrees F for medium-rare, about 45 minutes, turning two or three times during roasting to ensure even cooking.
- Transfer to a cutting board; let rest for 10 minutes. Remove the string.
- Place herbs on a large plate.
- Coat the tenderloin evenly with mustard; then roll in the herbs, pressing gently to adhere.
- Slice and serve.