Potluck Black Bean Soup

Our all day planning meeting for Transition Port Gardner called for some hearty soup for lunch. The black beans and spices aren't local, sorry, but everything else is. I got requests for the recipe, so here it is TPGers!

Potluck Black Bean & Corn Soup

2 cups dried black beans, rinsed, picked over and soaked overnight
1 Tablespoon olive oil
1 onion, chopped (Washington)
2-4 cloves garlic, chopped (our garden), unless you've got someone in the crowd who is allergic to garlic (you know who you are, Mimi!), in which case you can omit this
1 Tablespoon chili powder
1 teaspoon freshly ground cumin
1 teaspoon freshly ground coriander
1/2 teaspoon cinnamon
salt & freshly ground pepper to taste
1 large can (28 ounces) Muir Glen tomato puree (Sedro Woolley)
2 cups corn (frozen, local)

Drain the beans from the soaking water, put into a large pot and add fresh water to cover, bring to a boil, reduce the heat to a simmer and cook about 1 hour or until done. (Or put into a slow cooker and cook overnight; refrigerate until you are ready to finish the soup.) In a large cast iron skillet, heat the olive oil over medium heat. Add the onions and garlic (if you are using it) and spices, and cook until the onions are soft, about 6 minutes.
Add the onion mixture, tomatoes and corn to the cooked beans, cook about 8 hours in a slow cooker, or 1 hour on the stove. Take out about 1/3 of the soup and blend in a blender until smooth and return to the pot; or use your immersion blender for a short couple bursts. This will thicken the soup.
Toppings:
Put into bowls for people to top off their soup: salsa, sour cream, grated cheddar (all local, of course!)
Note: I like to grind my cumin and coriander fresh each time from seed. I have a small mortar & pestle, and it doesn't really take that long to grind up a teaspoon of each. There is so much more flavor this way than in that very old bottle of ground cumin you have in the back of your cupboard!