Mix together all marinade ingredients in a glass container. Add in meat. Marinate for 2 hours before cooking. Don't marinate for longer than 2 hours or meat will become mealy.
Heat cast iron grill pan over high heat. Also preheat oven to 375°F. Add enough oil to coat the grates. Add meat to pan and cook for 4-5 minutes per side. Finish cooking in the oven until internal temperature reaches 120°F. Let rest 10 minutes. Slice into ¼" slices and serve with chimichurri.
Alternatively, you can cook this on the grill. Cook over medium high heat for 6-7 minutes per side or until internal temperature reaches 120°F. for medium-rare. Let rest for 10 minutes. Slice into ¼" slices and serve with chimichurri.
Chimichurri
Make sure all finely chopped ingredients are really finely chopped!
Mix together shallots, garlic, peppers, and salt in a small/medium glass bowl. Add red wine vinegar and let it sit for 5 minutes.
Add in cilantro, parsley and olive oil. Mix until well-combined. Refrigerate until ready to use.
Pull out of the refrigerator 15-20 minutes before serving to let the olive oil soften.
To freeze: add chimichurri to small freezer-safe container. Pour a layer of olive oil over the top. Cover with plastic wrap touching the olive oil and place lid on container. Freeze for up to 3 months. The color may change a bit but the flavor will still be there.