I love Steak au Poivre and here's the recipe I use a bit of butter and a bit of olive oil in the pan. The butter gives it a nice flavor and the oil keeps it from burning.
I heat the oil/butter in the pan until it's sizzleing, but not smoking. Then I put the steaks in and shake the pan back and forth so the steaks don't stick. For a med-rare steak I sear the steak on each side 3 minutes while shaking the pan on a high heat, then turn the heat down to medium and cook each side 3 minutes more. A total of 12 minutes for a perfect steak

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Watch out when you flame the cognac! My friend once singed his eyebrows making this recipe

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Steak Au Poivre
Recipe by the late James Beard
2 (12 oz.) Boneless Strip Sirloin, thawed
1.5 T. coarsely ground pepper
1 t. salt
Oil
1/3 cup Armagnac, Cognac, or bourbon, warmed
Although it can be grilled with success, traditionally steak au poivre is panbroiled or sauteed. The pepper for steak au poivre must be crushed in a mortar, cracked with a rolling pin, or whirled in a blender to make rather coarse pieces. Do not be afraid to use a generous amount. Freshly crushed pepper is not hot.
About 30 minutes before cooking press the crushed peppercorns into both sides of the steak, using the heel of your hand. Gauge about 1 tsp. per steak.
Heat a heavy skillet with a very small amount of oil. Sear the steak on both sides very quickly over high heat. Reduce the heat and cook to the state you prefer. When the steak is done, quickly flame it with the warm liquor. Remove the steak to a hot platter, rinse the pan with a touch of the same liquor and pour over the steak. Serves 2.