- Heat the oil in a heavy cast-iron skillet over high heat. When it begins to smoke, sear both sides of the steak.
- Transfer the steak to a baking sheet and cook at 425°F for exactly 20 minutes.
- Take out of the oven, cover with aluminum foil and let sit for 15 minutes.
- Slice and serve.
- In a bowl (or food processor), cream the butter, garlic, shallot, mustard, parsley, rosemary and pepper flakes together.
- Place the butter on a sheet of parchment paper and roll out into a cylinder, about 2 cm in diameter.
- Refrigerate at least 2 hours.
- When it’s time to serve, slice the butter about 0.5 cm thick and put directly onto the steak, letting it melt slowly.
If you don’t have a heavy skillet, place the meat on a baking sheet and cook at 500°F for 10 minutes. Next, leave the steak in the oven, lowering the temperature to 425°F, and cook 15 minutes more.