For a healthier alternative to sour cream, try mixing in nonfat Greek yogurt.
Combine the garlic, cumin, beans, sour cream, cilantro, lime juice and salt in a small food processor. Add 1/4 cup warm water and puree until smooth. Taste for seasoning.
Transfer the dip to a bowl and garnish with a dollop of sour cream. Serve alongside corn tortilla chips.