Black Pepper Sauce
Make the black pepper sauce first. Heat the oil over medium heat in a small saucepan, then add the black pepper. Cook, stirring constantly, until the whites of the insides of the peppercorns turn brown.
Stir in the water, soy sauce and sugar. Bring to a boil and taste, adding a pinch of salt if necessary, or a bit more sugar.
Stir in the cornstarch and water mixture and boil one minute.
Set the sauce aside and cook the steak.
Preheat the oven to 400 F.
Salt the steak to taste.
Heat the oil in a cast iron skillet or other ovenproof heavy skillet until you see just a whisp of smoke. Add the steak and sear a few minutes on each side. Then use tongs to lift the steak up and sear the edges a bit as well.
Place the steak back in the pan and put the pan in the oven for 4 minutes. Turn the steak and cook another 4 minutes. (Internal temperature should be about 170.) Take the steak out and let it rest ten minutes.
Cut the steak into thin slices and serve with the black peppers sauce.