Add the parsley, cilantro, garlic, jalapeno, onion, salt, 4 tablespoons olive oil, and vinegar to a food processor or blender and process until nearly smooth.

Pour half of the mixture into a small dish, cover, and refrigerate until ready to serve.

Add the pork tenderloin to a large zip top bag and add the remaining half of the chimichurri to the bag. Coat the pork in the sauce, seal bag, and refrigerate for at least 4 hours.

Preheat oven to 425 degrees. Heat a cast iron skillet over high heat.

Add the remaining tablespoon of oil to the skillet and heat until shimmering. Add the pork and sear on all sides, about 3 minutes per side, until golden brown.

Transfer skillet to oven and bake for 15-20 minutes or until pork reaches 145 degrees.

Let rest for 5 minutes before slicing and serving with reserved chimichurri.