How to Make It
In a saucepan, whisk the water into the tomato paste. Add the carrots, onions, cabbage, celery, fennel stems, thyme and garlic. Season with salt and cook over low heat for 1 hour. Strain the broth into another large saucepan and discard the vegetables.
Bring the broth to a boil. Add the carrots, parsnip, sliced fennel and onion. Reduce the heat to moderate, cover and simmer until the vegetables are tender, about 5 minutes. Add the zucchini and tomatoes, cover and simmer for 3 minutes longer. Season with salt and pepper.
Ladle the soup into shallow bowls and stir about 1/2 tablespoon of the Pistachio Pistou into each bowl. Top with the Parmesan shavings and serve.
To make the soup a little richer, add a Parmesan rind to the broth along with the vegetables and herbs and strain it out after everything simmers. If you would like to make the soup more substantial, add cooked rice or beans.