Thanks Andy. I didn't realise wine was acidic. (If I had I wouldn't have used it because we just bought the pot and were trying to keep acidic food off it for a while yet. I hope it hasn't taken too much of the seasoning off it.)
Suprisingly, the beans taste OK.
Last night I cooked some broad beans in a cast iron pot with flour, butter, white wine and oregano. Throughout the process they gradually turned black, and they now look like they've been cooked in squid ink! :wacko: I would really like to know what turned them black. I assume it's the cast iron...