Heat olive oil over medium high heat in a dutch oven or soup pot. Add sweet potato cubes, onion and celery. Cook for about 5 minutes, or until onion and celery are soft (stirring often).
Add garlic, chili powder, cumin, oregano, cayenne pepper and salt. Stir well to combine.
Add vegetable broth, tomatoes with juices and black beans. Bring to a boil. Reduce heat to maintain a gentle simmer and cover.
Simmer for 20 to 25 minutes, or until sweet potatoes are tender.
Garnish with chopped fresh cilantro, if desired.