Put the ingredients in a large bowl, add the steaks and coat evenly. Cover and chill in the fridge for 3-4 hours.
Half an hour before cooking, take it out of the refrigerator.
Heat your griddle pan, grill or BBQ and cook it on both sides, for about 3-5 minutes, depending how well cooked you like your meat.
Rub the steak with the butter or spread and let it melt, then remove from the heat to a plate. Cover with foil and rest for several 5 minutes.
Serve with seasonal vegetables and the cooking juices poured on top.