Combine all the marinade ingredients in a bowl and mix together. Add the flank steak and stir to coat. Let marinade for at least 4 hours, but up to overnight.
Let flank steak sit at room temperature for 30-60 minutes before grilling.
Heat the grill to 500+ degrees. It should be as hot as you can get it for the perfect char on the outside.
Place the steak on the grill and cook for 3-5 minutes per side for rare to medium rare. I cook for 3 minutes per side because I like my steak very rare. For medium rare, it should have a 130-135 degree internal temperature.
Remove from the grill and let rest for 10 minutes. Yes, 10 minutes, You must be patient. The juices need time to redistribute through the meat.
Slice the beef against the grain and serve drizzled in chimichurri sauce.
Combine ingredients in a food processor or blender and puree.
Let the steak come to room temperature for at least 30 minutes before grilling. This helps get the nice sear on the outside to seal in the juices.
Make sure the grill is very hot (500+) before placing your steak on it. We want a nice crust on the outside.
Marinade for at least 4 hours for the best results. Recommend 6-12 hours for the marinade.
Let the steak rest for at least 10 minutes before slicing. If you cut into it before then you will lose a lot of your juices.