Your beef should be about one inch and a half thick. Sprinkle with salt and oil it; grill it on a moderate fire.
Put in a small saucepan a chopped shallot and half a glass of white wine. Cook it so that it is reduced to a spoonful. Also poach the marrow of a bone, and cut it in slices. Add them to the sauce with a little piece of butter, seasoning, and a little chopped parsley. Cook for a few minutes and put it over the entrecôte.