Heat a soup pot over medium heat. Add oil. When oil is hot, add onion. Saute onions 5 minutes. Add broth, tomatoes, black beans and pumpkin puree. Stir to combine ingredients and bring soup to a boil. Reduce heat to medium low and stir in cream, curry, cumin, cayenne and salt, to taste. Simmer 5 minutes, adjust seasonings and serve garnished with chopped chives.