Heat the oil in a frying pan. Season the steak on both sides with salt and fry it for 4-8 minutes depending on how well done you like it.
Transfer the steak onto a plate, cover with foil and rest for 10 minutes.
Meanwhile blanch the spinach in boiling water for 2 minutes, drain and squeeze the water out.
Put the spinach back in the pan, add the créme fraiche, the grated nutmeg and crumble the cheese over it. Season to taste and stir. cover and keep warm.
Heat the frying pan, add the collected juice of the meat and the port. Reduce it to a thick sauce.
Place the steak on a serving plate, drizzle with the sauce and spoon some spinach mixture on top.
Serve with some extra blue cheese scattered over it.