In a heavy medium skillet, melt 1/2 tablespoon of the butter in 1/2 tablespoon of the oil. Rub the steaks on both sides with the pepper. When the skillet is very hot, add the steaks, cover partially, and cook over high heat until a crust forms on the bottom, about 2 minutes. Turn the steaks over and cook, partially covered, until nicely crusted on the other side, about 2 minutes. Continue cooking over moderate heat, turning once, for about 2 minutes per side for medium-rare. Transfer the steaks to a plate and keep warm.