Pat the tenderloin dry and rub the paste all over it. Tie with kitchen twine to hold it together if needed. A lot of times they will come in 2 smaller pieces.
1 ½-2 pounds pork tenderloin
Cook the Tenderloin
Heat an oven proof or cast iron skillet with 2 tablespoons of olive oil over medium-high heat. Once the oil is hot and shining, sear the tenderloin on all sides until browned. About 2-3 minutes per side.
2 tablespoons olive oil
Put the whole pan in the oven and bake for about 18-24 minutes or until the pork reads 145 F in the center.
Transfer the pork to a plate or cutting board and tent loosely with foil. The Pork will continue cooking while it rests.
For the Sauce
Set the skillet back on the stove over medium high heat and add the olive oil. Once heated add the red onion and sauté until tender, about 2-3 minutes.
1 tablespoons olive oil, ¼ cup diced red onion
Pour the broth, red wine vinegar, rosemary, and pepper into the pan and bring to a boil. Reduce heat to a simmer and cook until the sauce has reduced by about half.
½ cup vegetable broth, 2 tablespoons red wine vinegar, 1 sprig rosemary, ¼ teaspoon coarse ground pepper
Stir in the butter and remove from the heat. Strain the sauce through a fine mesh strainer, if desired. If you don't strain the sauce, remove the rosemary sprig before serving.
4 tablespoons salted butter
For Serving
Slice the pork into 1- 1 ½ inch slices with sauce poured over top. Serve with your favorite veggies and mashed potatoes.
Notes
General Notes:
There's a shiny silver/white membrane on pork tenderloin. If you don’t remove this the pork won’t render right and the outside will be tough.
Make sure to use a pork tenderloin and not just a pork loin roast. Tenderloin is much more tender and juicier.
The larger your pork tenderloin is the longer it will take to cook in the oven. Use a meat thermometer and pull out at the right temperature (145 degrees) to make sure it’s as moist and tender as possible.
You can use a mortar and pestle to grind the herbs into a paste instead of using a food processor.
I highly recommend using fresh herbs. If you use dried herbs use ¼ of the amount listed. You will not get a good paste this way though.
Storage and Reheating:
Store leftovers in an airtight container for up to 3 days. For best reheating, heat in an air fryer at 360 for about 3-4 minutes.
The sauce will not reheat as nicely as it may separate a bit but still taste good.
The sauce will not freeze.
Freeze meat in a freezer safe bag or container for up to 2 months. Thaw overnight in the fridge before reheating.