2) Add 1/4 teaspoon of the black pepper, 1/2 teaspoon of the salt and the crushed red pepper. Remove 240ml of the chimichurri sauce from the processor and transfer to a non-reactive bowl, cover with clingfilm and reserve at room temperature for up to 6 hours. (If cooking the steak another day, refrigerate the sauce and return it to room temperature before serving.)
3) Season the steak with 1 teaspoon of the salt and 1/4 teaspoon of the black pepper on each side, and place in a large, resealable plastic bag. Add the remaining chimichurri sauce from the processor. Seal the bag and refrigerate the steak for at least 2 hours and up to 4 hours.
4) Once the steak has finished marinating, remove it from the refrigerator and allow it come to room temperature for 30 minutes. Meanwhile, preheat a griddle to medium heat.
5) Brush the excess chimichurri sauce off the steak and set the steak over the hot griddle. Cook for 6 minutes on the first side. Rotate the steak 45 degrees and cook for another 6 minutes. Turn the steak over and continue to cook until the steak is done, about 6-8 minutes for medium-rare.
6) Once cooked, lay the steak on a clean cutting board and allow it to rest for 5-7 minutes before slicing across the grain into 5cm-wide strips. Serve with crusty bread and the reserved chimichurri sauce.