http://www.cookingchanneltv.com/recipes/david-rocco/la-ribolitta-1959144
In a large pot, heat the 1 cup extra-virgin olive oil and saute the onion, garlic, celery and carrot, until they are soft. Add the potato, savoy cabbage, black cabbage, tomato puree and beans. With the back of a fork, break up some of the beans. Add the vegetable broth and bring it to a boil. Add the slices of the country-style bread and stir well. Continue cooking on medium heat for 45 minutes, adding a little more vegetable broth, if necessary. The consistency should be that of porridge. Season with salt and pepper, to taste. Drizzle extra-virgin olive oil on each individual serving and serve immediately.