Marinade it in red wine and oregano overnight before cooking it. Drain it, but keep the marinade. Brown the fillet in a pan with a little bit of oil, then cover it in foil and put it in the oven to finish for 20-30 minute - the foil needed to keep it from drying out. Don't wash the pan you brown it in - add the marinade, a tin of chopped plum tomatoes and a couple of good desert spoons of creme fraise or yogurt to the marinade and then reduce it by heat till it is beginning to thicken but still liquid enough to spoon over the fillet when you serve it.