I once had turtles about that size cooked in whole on a dinner table I was invited to in very fancy restaurant in Shanghai. My (european) boss more or less ordered me to at least try ANYTHING our chinese partners would offer us, so I did. Reminded me of jellyfish, more or less fully gristle without much of a distinctive taste. My guess was this was a revenge for the roasted pork knuckles we served them the year before, when they visited us...
But if you don't mind, where did you live? In China