Ingredients
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2 tablespoons unsalted butter
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2 tablespoons olive oil
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2 sirloin steaks, each about 1 1/2 pounds (thick-cut, bone-in top sirloin)
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kosher sea salt, to taste
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fresh ground black pepper, to taste
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3 tablespoons unsalted butter
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4 shallots, finely chopped
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1/4 cup beef stock
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2 tablespoons green mustard, with herbs or 2 tablespoons Dijon mustard
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3 tablespoons chopped mixed fresh flat-leaf parsley, chervil, and tarragon
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kosher sea salt, to taste
Instructions
- In a cast-iron frying pan over high heat, melt the butter with the olive oil until the mixture turns a light brown.
- Add the steaks and sear well, about 1 minute.
- Turn, sprinkle with sea salt, and brown on the second side for 1 minute more.
- Turn again, reduce the heat slightly, and cook, turning once, for about 6 minutes on each side for rare, or until done to your liking.
- Transfer to a platter, tent with aluminum foil, and let rest for 5 to 8 minutes before carving.
- Meanwhile, make the sauce: In a saucepan over medium heat, melt 2 tablespoons of the butter.
- Add the shallots and saute until softened but not colored, about 30 seconds.
- Add the stock, bring to a boil and cook until reduced by half.
- Remove from the heat and stir in the mustard, the remaining 1 tablespoon of butter, and the herbs.
- Stir in any juice that has collected on the platter holding the beef.
- Season with salt and pepper; pour into a warmed bowl.
- Transfer the steaks to an attractive cutting board and sprinkle them with pepper, then carry the board to the table.
- Cut along the bone to free the meat then carve in slices diagonally across the grain. Pass the sauce at the table.