Excellent review from Ralph Moore, but I feel I should point out that Callas did indeed sing Turandot on stage, indeed 23 times between 1948 and 1949. She also sang Butterfly on stage, in Chicago in 1955, the scene of the famous photo that has her exploding after a process server stuffed a summons into the belt of her kimono as she exited the stage.
This no doubt contributed to her decision not to sing the role again.