Chimichurri -- recipe here: http://www.mashupmom.com/seared-ahi-tuna-with-chimichurri-gluten-free-dairy-free-delicious/ (sans cayenne, juice of ¼ lime, and mixed chunkier in the food chopper rather than the food processor)
Take half the prepared chimichurri and thin it out with 1 tablespoon olive oil.
Place pork loin in gallon plastic bag, add thinned out chimichurri, seal, and marinate in refrigerator for at least one hour.
Spray roasting pan with cooking spray and place marinated pork loin in the middle, fat side down.
Cut potatoes into chunks and place in large bowl.
In a smaller bowl, mix together olive oil, lime juice, salt, chili powder, garlic, and chopped jalapeño. Pour over potatoes and toss until well coated.
Arrange potatoes around pork and roast for one hour at 400 degrees, or until meat reaches an internal temperature of 145 degrees.
Rest for 10 minutes before carving, then serve with the other half of the chimichurri.