1.Heat juice in a large saucepan on medium. Saute onion in juice for 2-3 minutes until tender. Add celery, carrots, garlic and oregano. Cook, stirring, for 3 minutes.
2.Add tomatoes and water and stir. Bring to a boil. Reduce heat and simmer for 30 minutes. Add all beans and simmer for a further 2-3 minutes or until vegetables are tender.
3.Season to taste. Top with crispy prosciutto, if desired. Serve with crusty bread.
To crisp prosciutto, place slices on an oven tray and bake at 180°C for 5-8 minutes. Allow to cool, then roughly chop. The cooked prosciutto can be stored in an airtight container in the fridge for up to 3 days. If you prefer a thicker soup, add potatoes and adjust cooking time.