1. In a small bowl, combine the olive oil, red wine vinegar, cilantro, cumin, garlic, salt and pepper.
2. Place the steak in a resealable plastic bag and pour the marinade over it. Seal the bag and refrigerate, for at least 30 minutes or overnight.
3. Preheat grill to medium high.
4. Place the steak on the hot grill and cook for about 7 minutes on each side for medium doneness.
5. Remove from heat and allow the steak to rest for 5 minutes before slicing it on the bias.
6. Have everyone build their own burrito with the warm tortillas, sliced steak, cheese, lettuce, guacamole, salsa and nonfat sour cream.Serving Size: 1 burrito