Salsa Verde Tomatillo

1. Heat oil in a large saucepan, over a moderate flame.
2. Add onions and cook until tender.
3. Add spinach, tomatillos, chiles, garlic, and oregano.
4. Cover and simmer for 5 minutes, stirring occaisionally.
5. Pureei in a food processor, until smooth.
6. Return to saucepan, stir in broth.
7. Heat to a boil, reduce heat, and simmer for 10 minutes remove from heat, stir in sour cream.
8. Serve slightly chilled.