With the back of a heavy saucepan, crush the white and black peppercorns. Remove most of fat from the steaks. Season with salt and crushed peppercorns.
Heat a large heavy saucepan. Pour in oil, and over high heat, cook the steaks 4 minutes on each side for medium rare. Transfer meat to a warm platter and reserve.
Carefully discard grease in pan and deglaze with Port. Simmer until reduced by half. Add cream and veal stock and continue to reduce until sauce is thick enough to coat the back of a spoon. Whisk in butter, 1 small piece at a time. Season, to taste, with salt.
Place 1 steak on each warmed serving plate. Spoon sauce over steaks and sprinkle green peppercorns equally over each portion.