In a large pot, heat EVOO over medium-high. Add carrots, celery, onion, red pepper, garlic and jalapeno and cook, stirring often, until vegetables are soft and fragrant, about 15 minutes. Puree vegetables with 3 cans black beans and 2 cups broth until smooth. Return to pot. Add remaining beans, broth, sweet potatoes and cilantro. Bring to a boil, then simmer until heated through and the mixture thickens, about 10 minutes. Season with salt and pepper and a dollop of yogurt.