Heat the grill to the highest temperature.
Take the entrecotes and brush them lightely with olive oil. Put them on the grill and grill about 2 minutes at both sides.
Let them rest a few minutes and pet a few slices butter and the persillade on one side of the meat. Place the meat for a short while under a grill to melt the butter.
Serve with pommes Parisienne, baked in duck fat.