In a bowl, whisk together vinegar, parsley, shallot, garlic, oregano, red pepper, a pinch of salt and pepper and olive oil.
Pour half of the sauce into a separate container for finishing the pork.
Place the pork tenderloin(s) into the bowl with the remaining sauce mixture. Toss well to coat. Refrigerate 3-6 hours.
Preheat oven to 450.
Place marinated pork on a baking pan (I line mine w/ foil for easy cleanup). Place in the preheated oven for 10 minutes. Lower heat and continue cooking until it reaches your desired internal temperature (I prefer 150), approximately 10-15 minutes more.
Allow pork tenderloin(s) to rest at least 5 minutes. Slice. Top with reserved chimichurri just prior to serving.