Meanwhile, heat a cast-iron skillet over medium-high heat. Add steaks and cook until medium or medium-rare, 5 to 7 minutes. The last 2 minutes of cooking, add lemon halves, cut-side down, to pan to caramelize. Remove lemons and steak to a cutting board. Let steaks rest 5 minutes and slice against the grain in 1/4-inch-thick slices. Squeeze lemon over steaks and scatter the green olives on top.