Step 1

Pat the steaks dry and, if they are thick, gently press them down so that they are about 1-1/2 inches thick. Season the steaks all over with the salt.

Step 2

Seal the peppercorns inside a small plastic bag and place on a cutting board. Using a meat mallet or the bottom of a frying pan, pound the peppercorns until they are coarsely crushed. Press the crushed pepper evenly onto both sides of the steaks.

Step 3

In a large stainless steel or cast iron skillet, heat the oil over medium-high heat. When the oil is hot and shimmering, add the steaks and cook about 4 minutes on each side, turning only once, for medium-rare (or about 5 minutes per side for medium). Transfer the steaks to a plate and tent with foil.

Step 4

Pour off the excess fat from the pan but do not wipe clean. Lower the heat to medium-low and add the butter and shallots. Cook, stirring constantly with a wooden spoon and scraping up the brown bits, until the shallots are golden brown and softened, 2 to 3 minutes. Carefully add the Cognac (it may ignite) and boil, again stirring to scrape up the brown bits, until the liquid is reduced to a glaze and mostly absorbed by the shallots, a few minutes. Add the cream and mustard and gently boil until thickened, about 3 minutes. Stir in any meat juices that accumulated on the plate. Transfer the steaks to plates and spoon the sauce over top.