Hi:
I think you chopped liver fans will just have to do without. The reason your Grandmothers chopped liver tasted so good was because of all the chicken shmaltz and gribenes (you don't want to know what gribenes are) in it. Without fat I doubt any substitite will come close.
Having said all that you might try eggplant in place of , or in combination with, the green beans. I have had a tasty mock liver spread from a kosher distributor that lists eggplant as main ingredient. However this one also had lots of oil .