Chop the onion finely and mince the garlic cloves.
Heat oil in a skillet over medium heat until it shimmers and begins to ripple.
Add the chopped onion to the skillet and sauté for about 5-7 minutes until it becomes fragrant and turns translucent, with some edges starting to caramelize.
Stir in the minced garlic and cook for another 30 seconds until fragrant, filling the kitchen with a warm aroma.
Transfer the sautéed onion and garlic to the slow cooker, adding the rinsed black beans, vegetable broth, smoked paprika, and a pinch of salt.
Set the slow cooker to low and cook for 6-8 hours, until the beans are very tender and the broth has thickened into a smoky, velvety soup.
Once cooked, use an immersion blender to puree the soup directly in the slow cooker until smooth but still slightly textured, or transfer in batches to a blender and blend carefully.
Squeeze fresh lime juice into the soup, stir well, and taste for seasoning, adjusting salt if needed.
Ladle the hot soup into bowls and garnish with chopped cilantro or a dollop of sour cream if desired.
Enjoy your comforting bowl of smoky black bean soup, perfect for cozy evenings.
