To make the chimichurri, blitz the parsley, oregano, garlic, shallot and chilli flakes in a food processor or chop very finely by hand. Add 2 tbsp of the olive oil, the lemon juice, vinegar and some seasoning, and pulse to combine everything to a saucy consistency.
Rub the remaining oil and a little seasoning into the steaks. Heat a griddle or frying pan and cook the steaks for 2-3 mins on each side or until done to your liking. Rest for a few mins, then spoon over the sauce and serve with fries and salad.