Saute onion and celery in a large deep skillet until soft. Add zucchini and saute lightly. Add diced tomatoes, tomato sauce, 2 tbsp. tomato paste, garlic and herbs. Stir to combine. Simmer on low heat for 25-30 minutes, stirring occasionally. Sprinkle with parmesan cheese.
NOTE: This can be served as a side dish or can be added to pasta to make a delicious entree.