1. In a large soup pot, heat olive oil.
2. Saute the onion and garlic in the olive oil for about 4-5 minutes.
3. Add cumin and curry powder and saute for an additional 4-5 minutes.
4. Add broth, thyme, pumpkin puree, salt, pepper and sugar. Bring to a boil
5. Stir in the black beans and tomatoes.
6. Reduce heat. Cover and gently simmer for 15 minutes, stirring occasionally.
7. Remove from heat and let cool slightly.
8. Stir in or dollop on 1/4 cup nonfat sour cream and serve.