So today I tried one of my (as I have recently learned not so genuine) Indian dishes: Dal Makhni (also Dal Makhani).
There are different recipes, some mix urad beans with red kidney beans, I went for one that only called for urad beans.
Anyway, I soaked them (at room temperature) for at least 16 hours (simple, cold, tap water) and yet in the ready dish we found little black dry beans whose husk seemingly hadn't been affected by the water. The beans had all been "subsurface", though.
It was the only disappointment when we wanted to enjoy the dish. So I am wondering what else I could have done? Is there perhaps a way to "identify" these hard beans after soaking, or even before?