The night before you plan to make this soup, place the dried mixed beans in a large bowl. (You may purchase a bag of fancy beans already mixed, or invest in many bags of different beans to make your own -- dried beans are inexpensive.) Cover beans with water and soak overnight. (
Next morning, drain the water off your beans and you're ready to make your soup.
If you forget to soak your beans the night before, on the day of your soup-making, place the dried mixed beans in enough water to cover and bring to a boil in a large pot, boil for 3 minutes, then cover pot, turn off heat, and allow to sit for 2 hours. Then proceed with recipe.
In a very large soup pot, heat the olive oil, and add the onion, garlic, carrot, and celery and sauté until slightly softened.
Add the vegetable broth, beans, salt, and the dried herbs of your choice to the pot (marjoram, sage, rosemary, or thyme are all delicious; savory is supposed to reduce the gassy effects of beans; basil and oregano, along with a can of chopped tomatoes added in the last half hour of cooking, will give your soup a delightful Italian flavor). This recipe can be adjusted in infinite ways to suit your tastes. Toss in 1 or 2 chipotle peppers if you like (they give a wonderful smoky taste as well as some additional heat).
Bring soup to a boil, then reduce heat, cover, and simmer about 2 hours, or until beans are tender, adding more broth if necessary to thin. Adjust seasoning and serve hot. With crusty bread and a salad, you have a meal. (This soup may also be pureed in a blender: remove chilies before blending, if you used them, and puree all or part of the soup, adding half-and-half, if desired, for an extra-creamy version.)