1. Stir together parsley, oil, cilantro, garlic, jalapeño, lemon juice, red wine vinegar, oregano, salt, pepper and hot pepper flakes.
2. Transfer flank steak and half of the chimichurri sauce to resealable plastic bag; refrigerate for at least 2 hours or overnight. Remove from marinade; shake off excess marinade and discard.
3. Preheat CRUX Panini Grill. Wearing oven mitts, carefully open lid and center flank steak on lower grill plate. Press handle several times during cooking time to grill steak on both sides. Cook for 12 to 15 minutes for medium-rare or until desired doneness. Let cool completely and slice thinly across the grain. Let cool (clean grill plates according to instruction manual).
4. Preheat panini grill. Arrange steak slices evenly down along center of each tortilla, leaving 1-inch border. Top with rice, remaining chimichurri sauce, cheese, tomatoes, lettuce, corn and red onion. Drizzle with sour cream. Fold up bottom of tortilla over filling, then fold in sides and roll up tightly starting from bottom.
5. Wearing oven mitts, carefully open lid and center 2 burritos on lower grill plate. Press handle several times during cooking time to press burritos. Cook for 6 to 8 minutes or until cheese melts and tortillas are crispy. Carefully remove with oven mitts. Repeat with remaining burritos.