Place the dry black beans in a stock pot and cover with the 6 cups of water. Bring to a boil on high heat and boil for 2 minutes. Cover with a lid and turn heat off. Let the beans soak for 2 hours. After 2 hours, drain and rinse the black beans and set aside.
In another stock pot, add the olive oil and heat on medium/high. Add the died onion, bell pepper, cumin, and chili powder to the pot and sauté for 2-3 minutes, or until the onion softens and is translucent. Add the green chilis and garlic and sauté for another minute. Add the diced tomato, vegetable broth, and soaked black beans. Bring to a simmer and cover. Let cook for 1 hour on medium heat, stirring occasionally. Watch the soup to make sure that liquid levels do not get to low. If they do, add more water.
Soup is ready when the black beans are tender.
Place half of the soup in a blender and puree until very smooth.
Add pureed soup back into the pot with the rest of the soup and stir together, adding more vegetable broth if a thinner consistency is desired.
Add salt to taste. Serve with toppings.