Two to four hours before you plan to cook the pork, marinate the pork and make the sauce.
Coat the pork with the garlic, olive oil, zest, juice, oregano, salt, and a few cracks of pepper.
Marinate in the refrigerator, removing 30 minutes before you plan to grill.
In a food processor or blender, pulse all of the chimichurri ingredients until finely chopped and smooth in texture. Taste and add more salt or lime if needed.
Set aside at room temperature.
Turn on the grill, or broiler if you don’t have a grill, and allow to get hot. Remove pork from the marinade, shaking off excess. Grill or broil the pork for 15-25 minutes, until inside is light pink. If broiling, I like to pan sear the tenderloin for 2-4 minutes per side on medium high heat before putting in the oven. Temperature should register 145 F for medium rare or 160 for medium when done for either method.