Not to dismiss the experience of Brazil, but Korea believed you would die if you had an electric fan on with no windows open. Safe to say entire countries are not infallible either.
Brazilian here. It's not a superstition, I can see my wife's belly literally inflate if the process is not done correctly. I cook beans at least once a week, I've made mistakes and there's no way to hide it. We don't get them cooked from delivery as we don't know how they were prepared, lesson also learned the hard way.
That said, the process is soaking the beans in water for, at least, 10 hours. You have to change the water four or five times during this period and toss the water at the end.
On the other hand, adding bay leaves are totally a superstition. Saw my mother-in-law trying to hide she forgot to soak the beans overnight by adding bay leaves and my wife had a bad aftermath.
Brazilian here. It's not a superstition, I can see my wife's belly literally inflate if the process is not done correctly. I cook beans at least once a week, I've made mistakes and there's no way to hide it. We don't get them cooked from delivery as we don't know how they were prepared, lesson also learned the hard way.
That said, the process is soaking the beans in water for, at least, 10 hours. You have to change the water four or five times during this period and toss the water at the end.
On the other hand, adding bay leaves are totally a superstition. Saw my mother-in-law trying to hide she forgot to soak the beans overnight by adding bay leaves and my wife had a bad aftermath.