1 If it does not or it says ham must be cooked, cook the ham slices an additional 10 minutes. 2  You can use a meat thermometer to see when the ham steak is cooked enough. 3  It should reach 130°F, (55°C), when inserted in the middle of the steak.am steaks are just thick slices of ham cut from a whole or a half ham. The best ham steaks come from the center portion of the ham and are boneless. You can usually find ham steaks in the grocery store pre-cut or you can ask a butcher to slice off steaks for you from a whole or half ham.