1. In a large pot, heat the 1/4 cup oil over moderate heat. Add the onion and cook, stirring occasionally, until golden, about 10 minutes. Add the garlic, carrots, and celery.
2. Cook, stirring occasionally, for 5 minutes.
3. Add the zucchini and cabbage. Cook, stirring occasionally, until the vegetables start to soften, about 5 minutes longer.
4. Add the broth, beans, rice, potatoes, tomato paste, bay leaf, thyme, and salt to the pot. Bring to a boil.
5. Reduce the heat and simmer, partially covered, until the rice and vegetables are tender, about 15 minutes. Remove the bay leaf.
6. Stir the pepper into the soup. Sprinkle each bowlful with Parmesan and drizzle each with 1 teaspoon of the remaining oil.