Prepare chimichurri sauce first by placing garlic in food processor and grinding until finely chopped, then add cilantro, parsley, olive oil, lemon juice and grated peel, salt, and crushed red pepper and grind until well blended.
Reserve and refrigerate 1/4 cup sauce for serving and place remaining sauce in a resealable plastic bag with thawed steaks, rotating steaks for complete coating.
Seal bag and allow steaks to marinate in refrigerator for at least 15 minutes to at most 2 hours.
Remove steaks and discard remainder of marinade.
Cook steaks to your desired doneness – we recommend medium-rare – via your preferred cooking method or refer to our helpful guide on how to cook steak.
Rest for 5 minutes before slicing, then serve steaks with reserved, chilled chimichurri sauce.