Place all ingredients except oil in a food processor. Whizz until parsley is finely chopped, but not pureed - see video or photos. Alternatively chop parsley by hand.
Transfer into a small bowl. Add oil, gently stir. Set aside for 1 hour before use, overnight is even better!
Store in an airtight container in the refrigerator and use within 3 days (Note 3). Makes ¾ cup.
Take steak out of the fridge 30 minutes prior to cooking.
Heat BBQ or heavy based skillet with 1 tbsp vegetable or canola oil over high heat until smoking.
Sprinkle each side of steak generously with salt and pepper.
Add steak and cook to your liking.
Cook times: for steak 2cm / ⅘” thick, 2 min on each side for medium rare (until internal temp is 52C/125F, will rise to 54C/130F after resting) OR 2 ½ min each side for medium (internal temp 57C/135F, will rise to 60C/140F).
Transfer to a plate, cover loosely with foil and rest for 5 - 10 minutes.
Cut thin slices against the grain (see photo below) and serve with Chimichurri Sauce on the side so people can help themselves.
