In a heavy, 3-quart saucepan, combine the beans, broth, onion, chile, and pumpkin; bring to a simmer and cook for about 10 minutes, or until the onion softens.

Transfer the mixture to a blender or food processor and whirl until A thick and smooth. Return to the pan and add 1 teaspoon of the cumin; taste to determine if you desire the remaining cumin or salt.

Serve in bowls. If desired, garnish with a squeeze of lime, a dollop of sour cream, and a sprig of cilantro.