A relish made with olives and oranges is a rich, bright accompaniment to succulent sliced steak.
Whisk together honey and vinegar in a medium bowl; season with salt and pepper. Whisking constantly, pour in oil in a slow, steady stream; whisk until emulsified. Stir in onion, garlic, olives, orange, and parsley; set aside.
Season steak all over with 1 teaspoon salt and 1/2 teaspoon pepper. Coat a 12-inch seasoned cast-iron skillet with a thin layer of oil; heat over medium-high heat until very hot. Sear steak, turning once, 6 to 8 minutes per side for medium-rare. Transfer to a plate, and tent with foil; let stand 10 minutes before slicing.
To serve, cut steak against the grain into 1/4-inch-thick slices, and arrange on a platter. Spoon relish on top; garnish with parsley sprigs.