The night before, cover the beans with 2" of cold water.
The next day, drain and rinse the beans. Combine with 4 cups of vegetable broth in your slow cooker on low heat.
In a non-stick skillet over medium-high heat, cook the onion and bell peppers. Stir frequently until they are beginning to blacken (I like mine to be semi-charred!). Remove from heat, and add to the slow cooker.
Add the garlic, chipotle peppers, adobo sauce, cumin, paprika, 1 tsp salt, and pepper to the slow cooker. Stir to combine.
Cook on low for 7-8 hours, or high for 3-4 hours.
When the beans are done, use an immersion blender (or normal blender) to blend ⅔ of the mixture. Add the lime juice, salt and pepper to taste, and stir well.
Serve with toppings of your choice.
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/slow-cooker-black-bean-soup/