Heat the olive oil over medium-low heat in a large, heavy-bottomed pot, and add the onions, carrot, celery and garlic. Cook until the vegetables have softened, about 10 minutes. Do not allow the vegetables to brown.
Add the tomatoes with the juice, parsley and ½ teaspoon sea salt. Cook for 5 minutes more, until the tomatoes are fragrant.
Add the stock and 2 teaspoons of sea salt and bring to a boil. Add the farro and the parmesan rind and bring to a boil again. Lower the heat so that the soup simmers. Cook about 15 minutes.
Add the zucchini and cook another 10 to 15 minutes, until the farro is tender but still has a little “toothiness.”
Add the cooked beans and heat through. Add more stock, if desired.
Add the chopped greens and stir until wilted. Adjust seasonings and serve with chopped basil leaves and freshly grated parmesan cheese and/or drizzled olive oil on top or a spoonful of pesto.