1
In a large stockpot, combine chicken broth, potatoes, onions, carrots, and celery (sliced, 1 inch thick).
2
Bring to a boil, then reduce heat to medium-high and simmer until potatoes are tender, about 30 minutes.
3
Add zucchini, tomato sauce, garlic, parsley, and cilantro.
4
Reduce heat to medium-low and cook for 10 to 15 minutes more, until zucchini is just tender.
5
Season to taste with black pepper and serve.