Place the beans in a pressure cooker with oil, onion, ginger, spices, tomatoes, broth and lime juice. Pressure cook for 8 min at 15 PSI and use natural release method, OR simmer on top of the stove for about an hour or until beans are soft.
Meanwhile, in a small bowl combine sour cream, cumin, cardamom and hot sauce (to taste) and set aside in the refrigerator.
When the soup cools enough to handle safely, blenderize a portion of it to make a thick, textured soup. You can use an immersion blender, food processor, or traditional blender for this step.
Serve soup with a dollop of the seasoned sour cream, plus lime wedges, avocado, and red onion for garnish. (Recipe♦193)