Combine vegetable broth or water, diced tomatoes, quinoa, onion, carrot, bell pepper, and Italian seasoning in a medium sauce pan.
Bring to a boil, then cover and simmer over medium low heat until all liquid has been absorbed (about 20 minutes).
Meanwhile, cut zucchini in half lengthwise and scoop out the seeds with a small spoon.
Preheat oven to 350 degrees.
When the quinoa is ready, stir in the Parmesan substitute. Adjust seasoning if necessary.
Spoon mixture into zucchini halves and top with vegan cheese, if desired.
Place in a baking dish. Spoon extra stuffing around the zucchini halves or bake in a separate dish.
Bake for 30 minutes.