Make the ricotta (you can make it ahead of time and keep it in the refrigerator if desired as this will help infuse the flavors, but it will still work if made and used right away). Soak sunflower seeds in boiling water for 20 minutes. Drain and rinse with cold water. Add the sunflower seeds and the next 5 vegan ricotta ingredients to a high-powered blender or food processor. Blend on high until no chunks of seeds remain, scraping down the sides as needed (you can add 1-2 tbsp. more water if necessary to obtain a creamy consistency). Transfer to a mixing bowl and stir in the remaining 3 ingredients. See the vegan ricotta cheese recipe post for more information and instructional photographs.
Preheat oven to 400° F (if you are making the ricotta at the same time as the baked ziti, you can preheat the oven while the sunflower seeds are soaking). Add 1 cup of tomato sauce to the bottom of a 13" x 9" baking dish and spread around with a spoon.
Boil 3 qts. of water in a 5-qt. pot. Salt the water if desired. Par-cook the pasta for 4 minutes less than the package directs. For example, if the package's cooking time is 12 minutes, cook the pasta for 8 minutes. If the package gives a range, such as 9-11 minutes, use the average and subtract 4 (so in this case, the pasta would cook for 6 minutes). Drain pasta and return to pot.
Reserve 1 cup of tomato sauce and add the rest to the pasta. Reserve 1/4 cup of ricotta and add the rest to the pasta. Stir to combine.
Transfer the pasta to the baking dish. Use a spoon to dollop and lightly spread the 1/4 cup reserved ricotta randomly on top of the pasta. Spoon on the 1 cup reserved tomato sauce randomly on top of the pasta around the spots with ricotta.
Cover with foil and bake for 20 minutes. Uncover and bake for 10 minutes or until heated throughout (you should see bubbling). Garnish with fresh basil or parsley if desired.