Crush 1 tablespoon of whole black peppercorns with a mallet. Season 4 filet mignon steaks (170-225g each) with 1 heaping teaspoon of kosher salt and press the pepper onto both sides.
Heat 1 tablespoon of vegetable oil in a large skillet until hot. Sear the steaks for about 4 minutes per side, until they reach 130-135°F / 54-57°C for medium-rare. Transfer to a plate.
Lower the heat, melt 2 tablespoons of unsalted butter in the pan, and cook ⅓ cup of finely chopped shallots until soft. Off the heat, add ½ cup of Cognac; return to the heat and reduce to a glaze.
Stir in ¾ cup of heavy cream and 1 teaspoon of Dijon mustard. Simmer until thickened, then spoon over the steaks.
