Chef stewart webb's roast pork tenderloin

1. Place tenderloin in olive oil with garlic, half the rosemary and cracked pepper.
2. Marinatei between four and 24 hours in the fridge.
3. Remove tenderloin and drain.
4. Preheat heavy skillet, sear pork on all sides, add mushrooms and place in shallow roasting pan and bake at 350f for 15-20 minutes.
5. In saucepan, reduce beef stock with herbs to half volume.
6. Seasoni with salt and pepper and whisk in butter.
7. Check seasoning to taste.
8. Remove pork from oven, slice across bias and place slices on a plate.
9. Cover with sauce, then top with mushrooms.