Black bean and corn soup

Mostly based off of a recipe from Savoring Mexico, by Marilyn Tausend.
Easiest. Soup. Ever. And full of beans!

2 tbsp canola oil
1 white onion, coarsely chopped
2-4 cloves garlic, coarsely chopped
8 cups canned black beans
3 cups chicken or veggie broth (I use Better Than Bouillon's No Chicken variety)
1 cup fresh or frozen corn kernels
salt and pepper and lime to taste

In a large heavy pot over medium heat, warm the oil. Add the onion and saute until softened, about 5 minutes (I sometimes brown them a bit). Add the garlic and saute for 1 minute. Transfer to a food processor or blender and add the beans (I use an immersion blender - I really love that thing. But if you use a blender or food processor, keep in mind that the heat may make the top of the blender want to come off, so be careful!). Puree until smooth. Transfer back to pot to warm the mixture. Add corn kernels, salt, and pepper. If too thick, thin with more water or broth.

Tasty things you may want to place on top:
Cheese, chiles, avocado, finely chopped onion, cilantro, or a big dollop of the following (for the spice lovers):
1 quart yogurt
7-oz can of chipotles en adobo.
Slice the chipotles into slivers (be careful - this is some hot stuff that is unpleasant when it gets under your nails, but really pleasant when it gets in your mouth. Wear gloves or wash your hands well after chopping). Mix with yogurt.