Step 1

Let steak sit at room temperature 30 minutes. Place peppercorns in a plastic bag and lightly crush with a rolling pin or meat mallet. Lightly brush steak with oil and season generously with kosher salt. Coat both sides with peppercorns, pressing to adhere. Let stand 15 minutes.

Step 2

Heat a cast-iron skillet over medium-high until very hot, 3 to 4 minutes. Swirl in oil. Add steak and cook, flipping once, until a thermometer reads 130°F (for medium-rare), 10 to 12 minutes total. Sear fat cap to finish, 1 to 2 minutes more. Transfer to a plate; tent with foil. Let rest 15 minutes before slicing so the juices redistribute. Remove skillet from heat and let cool slightly.

Step 3

While steak is resting, wipe skillet clean. Add butter and shallot to skillet and cook over medium, stirring often, until shallot softens, 1 to 2 minutes. Carefully add cognac and cook, scraping browned bits from pan, until almost evaporated, 2 to 3 minutes.

Step 4

Add Worcestershire, broth and any accumulated steak juices from plate. Reduce sauce to 1/2 cup, about 5 minutes. Stir in cream and cook, stirring, until thickened, about 1 minute more. Drizzle over sliced steak and serve with greens.