Prepare a medium to high temperature open flame grill, charcoal or wood. (The flames must get very close to the meat.)
Apply a generous amount of salt to the flank steak without rubbing it. (The salt must be loose or the meat will be too salty.)
Grill meat approximately 5 minutes on each side for medium rare, turning only once.
Once cooked, take steak in tongs and remove extra salt by slapping side of large knife against filet. Allow meat to rest 2-3 minutes before slicing it.
Using a large chef knife chop the parsley and cilantro. Place in bowl and add all other chimichurri ingredients.
Serve alongside steak.