Make the marinade by mixing the oil, garlic, soy sauce, vinegar, honey and salt and pepper and place the flank steak in and leave to marinade for up to 2 hours.
For the salsa verde, place the herbs, oil, anchovies, capers, vinegar and mustard in a blender and blitz to a rough sauce and set aside.
To cook the steak, place a large griddle pan over a large heat and leave for 5 minutes to heat up. Add oil and when it is smoking intensely, add in the steak and cook for 2 minutes on each side.
Remove from the pan and rest, then slice on an angle and serve with the salsa verde.