Originally Posted by CDSmith

I believe that means charred on the outside and "blue rare" or virtually raw on the inside.

My first job back in '79 was a short order cook. One guy used to come in every saturday and order up an 8 oz sirloin "blue rare".... you slap it on the grill, count to 10, then flip it over, count to 10, then serve it. (still mooing)