Rinse the beans and pick through them, discarding any debris. Place the beans in a 3-quart or larger slow cooker and fill it with water to about 2–3 inches above the beans. Cover and let sit overnight, or for 8–12 hours.
Pour the beans into a colander to discard the soaking water. Rinse and return the beans to the slow cooker.
Add the vegetable broth, olive oil, garlic, onion powder, cumin, chili powder, smoked paprika, and salt. Stir.
Cook on low for 8–10 hours or until the beans are cooked through.
Turn the slow cooker off and remove the lid to allow the beans to cool slightly.
Before pureeing, check the liquid level. Slow cookers can vary, so if you find that the liquid is still above the level of the beans when it comes time to puree them, you may want to skim a little of the liquid and reserve it for thinning later on.
With an immersion blender or by working in batches with a high-powered blender or food processor, carefully puree beans until your desired consistency is reached (you might like your beans to be 100% smooth, or chunky with a few beans still left whole).
Turn the slow cooker back on the low setting and let beans cook for another 30 minutes to thicken.
Check the consistency; if the beans are too thick, add additional vegetable broth and stir. If they're too thin, let them sit and cook for a little longer.
Taste and add additional salt if needed and squeeze half a lime over the beans right before serving, if desired.
Notes
To freeze: Allow the beans to cool, then freeze them in a large freezer bag or airtight plastic container. When you're ready to eat the beans again, take them out of the freezer and let them thaw in your refrigerator. If you’ve frozen the beans in a microwave-safe plastic container, you can use the thaw setting on your microwave to thaw them. Once thawed, cook the beans on the stovetop on medium heat until heated through or microwave in a microwave-safe container, stirring every 2–3 minutes, until heated through.
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