Heat a large pot over medium heat and add a splash of oil.
Sauté the chopped onion until translucent, about 5 minutes.
Add minced garlic and diced bell pepper, cooking for another 3 minutes.
Stir in the cooked black beans and mix well.
Pour in the vegetable broth and bring to a simmer.
Add cumin, chili powder, salt, and pepper.
Let the soup simmer for 20 minutes, stirring occasionally.
Use an immersion blender to puree the soup to your desired consistency.
Stir in lime juice and adjust seasoning as needed.
Serve hot, garnished with fresh cilantro.