I meant 500g of raw beans cooked. Given that there's a lot of water in them after, I do not know how much 500g of raw beans weighs when cooked.

Ah, makes sense. I'm from Brazil where rice & beans is a staple, but 500g sounds like a lot!

PSA: Raw beans are dangerous, especially kidney beans. Beans contain toxic lectins when uncooked.

I would hazard a guess that these: https://en.wikipedia.org/wiki/Black_turtle_bean are the beans in question. They work quite well as an alternative to refried beans in Tex-Mex style food.

Yes, black beans. And no, eating them uncooked would take quite a while, and be hard on the teeth. I suspect that "raw" referred to the weight basis.

But anyway, the are great fiber. Much more comfortable than grain fiber. But one must rinse them carefully after cooking, to reduce gassiness.