Place a soup or stock pot on the stove over medium heat and when it is hot, add the oil. Add an onion, carrots, celery, garlic, basil, oregano, and chili powder and cook about 10 minutes until the onion is soft.

Add the beans, water, and bouillon cube and raise the heat to high and bring to a boil. Turn the heat down to low and cook about 2 1/2 hours until the beans are very tender and the mixture is uniform in color.

If you want a pureed soup, set the soup aside to cool for about 20 minutes. Put 2 cups soup in a blender and put the top on, halfway (this will allow the soup to expand and any steam to escape) and blend until smooth. Transfer to a large container. Repeat using the rest of the soup.

Just before serving, squeeze the juice of 1/4 lime on each serving and a tablespoon of yogurt.