I start by dicing the onion, bell pepper, celery, and carrots into small, even pieces so they cook at the same rate. Mincing the garlic and jalapeño at this stage too saves me from stopping partway through. Having everything chopped and ready before I touch the crockpot makes the whole process go by so much faster.
I like to warm the olive oil in a skillet and sauté the onion and garlic for about 3 minutes until they turn fragrant and slightly golden. This step isn't required, but I find it deepens the flavor of the finished soup noticeably. If I'm short on time, I skip it and just toss everything in raw, and it still turns out great.
Next, I add the black beans, sautéed onion and garlic (or raw, if I skipped that step), bell pepper, celery, carrots, and jalapeño into the slow cooker. I pour in the broth and sprinkle in the smoked paprika, cumin, cayenne, salt, and pepper. A quick stir with a wooden spoon makes sure everything is evenly distributed before the lid goes on.
I set my crockpot to low for 6 hours, though high for 3 to 4 hours works just as well if I'm in more of a rush. The beans soften further and the vegetables practically melt into the broth as the smoky spices infuse everything. My kitchen smells incredible by the time this step is done
Once the cooking time is up, I grab my potato masher and mash some of the beans right in the pot until the soup reaches the consistency I want. For an ultra creamy texture, I'll use an immersion blender for a few quick pulses instead. I like leaving some texture, so I never fully puree it.
Right before serving, I stir in the fresh lime juice and chopped cilantro. This final step wakes up all the smoky, earthy flavors and adds a burst of freshness on top. I always taste at this point and add a pinch more salt if needed.