I was cooking up a little bit of red cabbage for dinner, a pho type soup that lacked bean sprouts for garnish...so I sliced up the cabbage really finely - well, my chef brother in law would not have called it a fine slicing, but by my standards it was, then I tossed it into boiling water, to which I then added salt.
Look carefully at the picture......
See the blue in the water?
That was SO cool! The water went really really blue, then a beautiful deeper and deeper blue until it went purple.
You should try it, it was beautiful...and yummy too.