In this recipe, big bold flavor is introduced only after cooking—we dot the just-cooked steaks with a compound butter made by mashing softened butter with miso, dry mustard and smoked paprika. As the meat rests, the juices mingle with the melting butter, creating a luscious, umami-rich sauce. Rather than serve the steaks as large hunks of meat, we slice and serve them on a salad of peppery watercress tossed with sesame seeds, soy sauce and rice vinegar. Note that the recipe calls for seasoned rice vinegar. If you have only regular rice vinegar, in the butter mixture, use an equal amount along with a pinch of white sugar; in the dressing, use 3½ tablespoons vinegar and ½ teaspoon white sugar, then season to taste with salt.