Mix the ingredients ( except the salt and pepper) in a bowl then add the steaks. Marinate for about an hour if you can.
Heat a heavy based frying pan or griddle pan. When piping hot, season the steaks and add to the pan. Cook for 30 seconds then turn over. Keep cooking and turning until it’s done to your liking ( this also depends on the thickness of the meat)
Transfer them to a plate and cover. Add some more port ( about 2 Tbsp) and a drop of water to the pan and reduce it to a thick sauce, scraping up the browned bits from the bottom with a wooden spoon.
Slice the steak and pour this sauce over it just before serving.