Combine all the marinade ingredients in a medium size bowl until the salt and sugar dissolves thoroughly.
Place the flank steak into a large gallon sized freezer bag and then add the marinade. Massage the marinade around the meat and then refrigerate for at least 2 hours, but no longer than 24 hours.
Preheat your grill to 450 degrees F. Grill the steak for 4-5 minutes per side, or until an internal thermometer reads 130-135 degrees F for medium rare or around 145 degrees for medium. Once the steak reaches your desired temperature, remove the steak from the grill and allow it to rest for 10-15 minutes.
Slice the steak into thin strips against the grain (perpendicular to the long strands of muscle).