To test for doneness, make a small incision in the thickest part of the steak with the tip of a paring knife. It should be a little less cooked than you would like to allow for carry-over cooking. If using a meat thermometer, rare registers 125 to 130 degrees F. For medium rare, 135 to 140 degrees F and between 145 and 150 degrees F for medium. 155 to 160 degrees F for medium well and 165 degrees F and beyond for well done. Like your steak well done? Simply close the grill lid and cook longer to desired doneness.