Season bison sirloin steaks with salt and pepper. Heat the 1 tablespoon oil over medium heat in a large heavy skillet. Cook bison sirloin steaks in hot oil for 16 to 18 minutes or until an instant-read thermometer registers 145 degrees F, turning once. Top each bison steak with 1 tablespoon of the pesto. Cover skillet and let stand for 3 minutes. Remove bison sirloin steaks from skillet and thinly slice.