Place burgers on a hot grill and cook, without moving, for about 3 minutes. Use a spatula to turn the hamburger over. If using cheese, lay slices on the meat. Continue to cook until the burgers are cooked through, about another 3 to 4 minutes for medium-rare. Remove the burgers from the grill and allow to rest for a few minutes while you toast the buns. Top the burgers as you desire.