I was watching an old East German movie and one scene they were serving sweet and sour bean soup. [The movie was made and banned in 1965 and the setting would have probably been early 1960s. Not a bad movie. The Rabbit Is Me should you be interested in that sort of thing.]
Google has a few recipes but I was wondering what sort of beans they would have been using?
Good point - here is the recipe (in German) with a photo.
I think the only real difference to the other recipe is that they add sugar and vinegar - but that is what I meant.