In a food processor or blender, pulse beans with 1 cup water until a chunky puree forms.
Place 1 tablespoon of olive oil in a pot on medium-high heat, then saute onion and garlic for 1-2 minutes, or until onions are translucent and fragrant.
Pour bean mixture into your pot, followed by remaining ingredients: chili powder, salt, cilantro, lime juice, and cayenne.
Allow soup to simmer just until it is hot and bubbly. If you aren't serving your soup right away, and you find it is starting to dry out, feel free to add a splash of hot water.
Salt to taste.
Serve alone in a bowl, over chips, over rice, or topped with fresh cucumber and bell pepper.