Black Bean or Turtle Bean Salad

I got this bean from KAU ABARD extn. counter, Thrissur. They said it is Soy bean. Look at the stuff I harvested. I searched on the Internet and found that it is Black bean indeed. It is a Mexican favourite for salad. I cooked it to make a kind of Dal Makhani. But the bean was very hard to boil and finally I had to grind it in the mixer. I have sown the seeds again last week.