To make the sauce:
Heat oil in a large saucepan over medium heat. Add the onion, carrots and celery, season with salt and cook for 15-20 minutes, stirring occasionally, until caramelized. Add the diced tomatoes, tomato paste and season with your desired amount of basil, oregano and salt. Simmer for 20 minutes over medium-low heat, then turn off heat and set aside.
To make the tofu ricotta:
Blend all ingredients together in a food processor. Set aside.
To make the ziti:
Cook the pasta according to directions. Saute the zucchini in olive oil over medium heat until lightly browned.
Preheat the oven to 350 degrees. Toss the pasta and sauce together. Pour the pasta into a prepared 9x13 pan. Layer the zucchini on top, then dollop the tofu ricotta over the top, using your fingers to help spread it around evenly. Bake for 20 minutes until ricotta is browned.