Season a porter-house steak with salt and pepper and rub with butter. Place on a hot gridiron and let broil on a quick fire on both sides. Make this sauce: Chop 1 onion and brown in 1 tablespoonful of butter; add ½ cup of stock and ½ cup of claret; let boil well. Season and thicken the sauce with a little flour and some chopped parsley. Let boil up and serve at once with the steak.