Prepare the rosemary marinade: In a bowl, mix the olive oil with the finely chopped rosemary leaves. Generously rub this mixture over the pork tenderloin. If you have time, let it marinate in the refrigerator for at least 1 hour; if not, you can bake it right away. If marinating, remember to take it out of the fridge 30 minutes before baking so it comes to room temperature.

Preheat the oven to 350°F (180°C). Place the pork tenderloin on a baking sheet and bake for about 30-40 minutes. I served the tenderloin with garlic potatoes (you can find the recipe in my collection).