i was just going to try this dish and read your comment. The temperature definetely sounds off. However the canned beans are already salted, that was part of the problem. Thanks for the feed-back, I will probably tone down the vinegar!
First: I think there is a typo - after 20 minutes at 225 degrees, the fish was not just undercooked - it was still cold. After turning up the heat, it took about 45 minutes to get it completely cooked.
Second, the Black Beans were dreadful. We made this on a whim so we used 4 cans of (unseasoned) black beans. I used 1/4 cup of salt and only 1 cup of rice wine vinegar, and they were still so salty/vinegary that they were inedible, even after we drained them and rinsed the marinade off.