Soup - Jeanne's Minestrone di Romagna

1/3 cup olive oil
3 T butter
1 cup thinly sliced yellow onion
1 cup diced carrots (1 lge)
1 cup diced celery (3 stalks)
2 cups peeled, diced potatoes (2 lge)
1 1/2 cups canned cannellini beans
2 cups diced zucchini (2 med)
1 cup diced green beans
3 cups shredded cabbage
2 cups canned beef broth (I used chicken)
4 cups water
3/4 cup canned itlaian tomatoes with juice
1/2 cup freshly grated Parmesan

Put oil, butter, and onion in pot over med low heat until onion wilts and is pale gold, but not browned. Add carrots, cook 2-3 min, stirring once or twice. Repeat this procedure with the celery, potatoes, zucchini, and green beans, cooking each one a few minutes and stirring. Add shredded cabbage, cook about 6 mins, stirring occasionally. Add broth, some Parmesan cheese crust, tomatoes and juice, bit of salt. (I also like to add some paprika). Cover and cook at very slow boil for at least 3 hours. If necessary, you can stop the cooking at any time and resume later. Cook until soupy thick, adding water if necessary (not broth). Fifteen minutes before the soup is done, add beans. Just before turning off the heat, remove the crust, swirl in grated cheese, taste and correct for salt.