Preheat the oven to 450 degrees F. Heat the oil in large, wide oven-proof skillet or large, shallow roasting pan over medium-high heat. Carefully set in the potatoes slices, its ok if some slightly over lap. Cook 3-4 minutes on the stovetop, then place in the oven and cook 20 minutes. Turn the oven broil and cook until the potatoes are crispy on top.
To cook the steaks, place the pepper, thyme and salt on plate. Set on the steaks and coat with the mixture on both sides. Grill the steaks, lightly oil the surface if not non-stick, 2 to 3 minutes per side for rare; 3 to 4 for medium rare; and 5 minutes for medium. Drain the excess oil from the frites. Season the frites with salt; mound on plates beside the steaks