Cook onion, garlic, cumin and pepper flakes in oil in 4-quart saucepot over medium heat for 3 minutes or until onion is tender. Remove from heat. Place 1 can beans in blender, add 1/2 the broth. Cover, and blend until puréed. Stir into saucepot. Repeat with one more can of beans and broth. Stir in remaining can of beans , salsa, and lime juice. Heat mixture to boil. Reduce heat to low and stir in chopped cilantro. Simmer 30 minutes. Ladle soup into each bowl; top with dollop of sour cream. Garnish with broken tortilla chips and snipped cilantro.
