In a food processor or blender, combine beans, broth, salsa, cumin, lime juice, cilantro, and red pepper flakes (optional). Blend until fairly smooth. (**NOTE: I have tried this with an immersion mixer, blending the soup right in the pan and this also works.**)

Heat mixture in a sauce pan over medium heat until thoroughly heated through. Takes about 5-10 minutes.

Ladle soup into four bowls. Top each bowl with sour cream and green onions. The sour cream isn't necessary; however, if you do make the soup more spicy, the sour cream takes away some of the heat and lets the spice flavor actually come through which gives the soup a great taste.