In a mixing bowl, whisk together olive oil, garlic, lime juice, orange juice, cumin, chili powder, salt, black pepper, and cilantro to create the marinade.

Place the flank steak in a resealable plastic bag or shallow dish and pour the marinade over the steak. Seal the bag or cover the dish and refrigerate for at least 1 hour, preferably overnight.

Preheat the grill to high heat.

Remove the steak from the marinade and discard the marinade. Grill the steak for about 5-7 minutes on each side for medium-rare, or until desired doneness.

Remove the steak from the grill and let it rest for 5 minutes before slicing.

Slice the steak against the grain into thin strips.

Serve with pico de gallo, guacamole, sour cream, shredded cheese, and warm corn tortillas.