First prepare a beaten with celery, carrots and onion and garlic.
Peel the potatoes and cut them into cubes. Wash the cabbage and cut it first in half and then into strips.
In a saucepan, brown the batter with a little oil, add the potatoes and savoy cabbage. Cook for a few minutes on high heat to flavor them well.
Chop the rosemary and add it to the vegetables.
At this point add the farro which you will slightly toast, stirring, and the vegetable broth. Set aside some broth to adjust the consistency of the soup.
Season with salt and pepper.
Continue cooking over low heat, stirring occasionally, for about 30 minutes.
When the soup is cooked, pour it into the bowls and serve with the toasted croutons.