In a large saucepan, cover the beans with about 2 inches of water. Bring to a boil. Turn the heat off, cover the saucepan, and let the beans soak 1 hour. Drain the beans and set aside.

Cook the bacon in a large, heavy pot over medium-high heat. When the bacon has crisped, remove it to a paper towel-lined plate. Remove all but 1 tablespoon of the bacon fat from the pot. Add the onion, garlic, oregano, and cumin, and cook over medium heat until the onion is soft, about 5 minutes. Add the soaked beans, chicken broth, and cilantro to the pot and reduce the heat. Simmer, partially covered, for about 2 ½ hours, or until the beans have softened. 

Using an immersion blender, blend the soup to the consistency of your choice. If you want a thinner consistency, stir in a little more chicken broth or water. Stir in the reserved bacon, then add salt and pepper to taste. Serve with cilantro leaves scattered over top.