During the late 1960s to early 1970s, a flurry of adult-oriented animation hit the world. Films like Ralph Bakshi's Fritz the Cat and Heavy Traffic became box-office smashes. However, animators took it one extreme step further and produced what is basically animated pornography, much of which was produced in Europe. Some of these (such as Schwanzel and Gretel and Odysseus und die Konigin Von Pornos) have acquired cult followings in recent years due to their subversive content, while others (such as the more obscure shorts contained in the Dirty Little Adult Cartoons series) have been largely forgotten, but still exist.
However, artist Nancy Edell's 1969 effort, Black Pudding, is nowhere to be found. It's said to be an artistic animated short with strong sexual imagery but, other from that, little to no info on it exists.
The BFI entry reveals that the film originated in Britain and involved the "[a]nimated life-cycle of grotesque figures stressing the physical basis of life" as well as "a group of surreal beings take a startling journey through the immer recesses of an enormous nude female". The page also sheds light on more of the crew whom worked on the film. 
In addition to that, the Canadian film magazine "Cinema Canada" did an interview with Edell, included in it's February 1976 edition. In the interview she talks about the film's apparent success at film festivals and her inspiration from the pudding itself.