Soak the giant beans overnight, then drain and discard the soaking water. Now cook the beans in enough water for 1 - 1.5 hours until they are cooked through.
In the meantime, peel and dice the onion and garlic. Chop the kohlrabi and carrot greens. Peel and cut the kohlrabi and carrots.
Strain the vegetables and save the cooking water. Add the tomatoes and the chopped greens to the vegetables. Add enough of the cooking water until the consistency is good. Mix everything together, season to taste and heat. Drain the finished beans and add them.