PreparationMake roast: Put oven racks in upper and lower thirds of oven and preheat oven to 425°F. Pat roast dry and sprinkle with salt and pepper. Heat oil in skillet over moderately high heat until hot but not smoking, then sear roast until underside is browned, about 4 minutes. Turn meat over, then transfer skillet to upper rack of oven and roast until thermometer inserted 2 inches into center of meat registers 120°F, 20 to 25 minutes. Transfer to a cutting board and let stand 15 minutes. (Internal temperature of meat will rise to 130 to 135°F for medium-rare.) Make sauce while meat cooks: Toss together tomatoes, salt, red-pepper flakes, and 1/4 cup oil in a 13- by 9-inch glass baking dish. Roast on lower rack until tomatoes burst and release their juices, about 30 minutes. Meanwhile, pulse parsley and garlic with vinegar and remaining 2 tablespoons oil in a food processor until chopped, then transfer to a bowl. Stir tomatoes with their juices into parsley mixture. Slice roast across the grain and serve with sauce. Cooks' note:Leftover sauce keeps, covered and chilled, 5 days.
PreparationMake roast: Put oven racks in upper and lower thirds of oven and preheat oven to 425°F. Pat roast dry and sprinkle with salt and pepper. Heat oil in skillet over moderately high heat until hot but not smoking, then sear roast until underside is browned, about 4 minutes. Turn meat over, then transfer skillet to upper rack of oven and roast until thermometer inserted 2 inches into center of meat registers 120°F, 20 to 25 minutes. Transfer to a cutting board and let stand 15 minutes. (Internal temperature of meat will rise to 130 to 135°F for medium-rare.) Make sauce while meat cooks: Toss together tomatoes, salt, red-pepper flakes, and 1/4 cup oil in a 13- by 9-inch glass baking dish. Roast on lower rack until tomatoes burst and release their juices, about 30 minutes. Meanwhile, pulse parsley and garlic with vinegar and remaining 2 tablespoons oil in a food processor until chopped, then transfer to a bowl. Stir tomatoes with their juices into parsley mixture. Slice roast across the grain and serve with sauce. Cooks' note:Leftover sauce keeps, covered and chilled, 5 days.