We can only get either split skinned urad dal or whole urad dal with the black skin nearby, and it's been almost impossible to peel, even after prolonged soaking. I'm feeling quite disillusioned at the prospect of having to deal with it again, especially after my MIL herself said they were unusually tough skins and told me to go ahead and leave a few unpeeled because it was just not worth the time it took. We have a big bag of it and I don't want to be wasteful. But I also don't want black skins in my vadas. Is there anything I can try short of rubbing them for hours to no end? Last time I ended up peeling them one by one, but I am not sure it was worth it.