In a large saucepan, heat oil and sauté the onion, celery, garlic, carrot, and ham. Add the cabbage, Swiss chard, potato, 3 cups of the vegetable broth, tomato, rosemary, thyme, and bay leaf. Add more water if needed to cover the vegetables. Bring to boil; simmer for 15 to 20 minutes. Place about two thirds of the beans in a food processor with the remaining 1/2 cup of vegetable broth and process until smooth. Add the pureed beans and the remaining whole beans to the soup; simmer for about 5 minutes. Remove bay leaf and season with salt and pepper to taste. Makes 4 servings.