Preheat oven to 425 degrees. Place the pork tenderloin in a casserole dish. Stab the pork tenderloin with a fork.
In a food processor, blend the cilantro, garlic, red pepper flakes, lime juice, jalapeño and rice vinegar. Slowly drizzle in the olive oil with the food processor running. Pour half of the chimichurri over the pork tenderloin, turning to coat well.
Roast for 20 - 25 minutes or until the internal temperature reaches 145 degrees.
While the pork tenderloin in roasting, prepare the polenta.
Bring 4 cups of water to a boil. Gradually stir in the polenta, cooking for 3 minutes. Set aside.
Heat about 1 T of olive oil in a skillet over medium heat. Add the mustard greens and sauté until tender, about 5 minutes.
Add the cooked polenta and the butter to the skillet. Mix until smooth and creamy. Season generously with sea salt and ground pepper.
Remove the pork tenderloin from the oven and allow to rest (on a cutting board) for 5 minutes before slicing.
Spoon the polenta into bowls, top with sliced tenderloin and drizzle with the chimichurri. Enjoy immediately!