A peppery crust and a quick, easy pan sauce turn a midweek dinner into bistro night. This recipe makes enough steak for dinner tonight as well as for Steak Sandwich Wraps tomorrow or later in the week.
Preheat oven to 425 degrees. Place potatoes on a rimmed baking sheet and toss with 1 tablespoon oil; season with salt. Roast until golden brown and crisp, about 35 minutes, flipping halfway through.
Meanwhile, spread peppercorns on a large plate. Season steaks with salt, then press into pepper, coating both sides. In a large skillet, heat 1 tablespoon oil and butter over high. In 2 batches, cook steaks until medium rare, about 8 minutes, flipping once. Let rest on a cutting board, 5 to 10 minutes.
Discard fat from skillet, lightly wipe with a paper towel to remove any loose pepper, and heat over medium. Add wine and cook, stirring and scraping up browned bits with a wooden spoon, until wine is reduced by half, about 2 minutes. Add cream and cook until sauce coats back of spoon, about 4 minutes. Stir in mustard and season with salt.
Refrigerate 1 steak to use in the Steak Sandwich Wrap. Slice remaining steaks against the grain, divide among four plates, and top with sauce. Serve with potatoes and parsley.