Combine marinade ingredients in small bowl and whisk together. Put steak in a zip lock bag, pour marinade over the top of the steak. Close zip lock bag and allow steak to marinate in the refrigerator for at least 3 hours.
Prepare a grill to medium-high heat. Remove steak from marinade and grill to desired doneness, approximately 8 minutes per side for medium-rare.
Remove steak from grill and let rest for 10 minutes, the slice steak against the grain into thin slices.
Fill tortillas with steak, onion, pico de gallo, cilantro and Queso Fresco.