So, in her book Passionate Vegetarian, Crescent Dragonwagon has this soup called Eternal Soup, also known as The Soup in her Soup & Bread book. And you cook it, and just add in different veggies, etc. daily to change it up a bit.
I was hoping it, or something similar was on her blog (which is under construction at the moment). Instead, I found this helpful and interesting link (which incidentally does list three different soups), on a blog linked to her writing blog (I got a little distracted), enjoy.