• 1 lb. boneless top sirloin steak, trimmed
• ¾ teaspoon kosher salt, divided
• ½ teaspoon ground pepper, divided
• 1 tablespoon extra-virgin olive oil
• 1 ½ tablespoons butter
• 4 medium cloves garlic, minced
• 2 medium shallots, sliced lengthwise
• 1 sprig fresh rosemary, plus more for garnish
1. Pat dry with paper towels. Sprinkle with 1/2 teaspoon salt and 1/4 teaspoon pepper. Let steak stand at room temperature for 30 minutes.
2. In a large skillet, melt the butter with the oil over medium-high heat. When the butter foam subsides, add the steak. Sear until a brown crust forms, about 2 minutes per side. Using a strong pair of tongs, press the edge of the steak into the pan, rolling and cooking edges until the fat is rendered. Return steak to pan flat-side down, reduce heat to medium. Add garlic, shallots, and rosemary; cook, tilting the pan slightly to pool the butter and drippings on one side. Use a spoon to baste the steak with the butter mixture. Continue to cook, basting occasionally, until desired degree of doneness or an instant-read thermometer registers 125-130 degrees F for medium-rare. Cooking time will vary based on steak thickness. Transfer the steak to a clean cutting board and top with the shallots, garlic and rosemary. Cover loosely with foil; let stand for 10 minutes.
3. Discard the rosemary sprig. Thinly slice the steak against the grain and transfer to a serving platter. Spoon drippings from the pan and cutting board over the steak. Season with the remaining 1/4 teaspoon each salt and pepper and garnish with more rosemary, if desired.