Drain the soaked cashews and transfer them to a high-speed blender. Add the water and blend on high for 15-20 seconds or until smooth. Transfer to a large mixing bowl and set aside.
Heat the oil in a large non-stick skillet. Once hot, add the minced garlic and sauté for 2-3 minutes. Next, add the grated zucchini and season with salt.
Cook for 7-10 minutes or until the zucchini has reduced by about half and there is no more water (the zucchini will release some water during cooking).
Transfer the cooked grated zucchini to the cashew cream. Add the white vinegar, nutritional yeast, herbs, black pepper, and matcha if using. Note: matcha just gives the tart a brighter green color. It's optional and doesn't affect the flavor. Stir well to combine the zucchini with the cream and seasonings. At this point, you can taste it and adjust the saltiness to taste.
Unroll your pie crust (or flatten it, if homemade), and press it into an 8-inch pie plate, leaving about a 1-inch overhang.
Transfer the zucchini batter to the pie crust and use a spatula to spread it evenly. Bake for 50-60 minutes or until the crust is golden brown.
Let it cool a few minutes before serving warm! This tart is also delicious chilled! Keep the tart for up to 4 days in the refrigerator and serve cold, or reheat covered with aluminum foil in a 350°F (180°C) pre-heated oven for 20-30 minutes.
Notes
Color: The color of the tart tends to be more yellow than green after baking. If you want a more appetizing green color, add about 1/4 of a teaspoon of matcha. It won't affect the flavor at all and is completely optional.
Cook the zucchini enough. To prevent the filling from being watery, make sure to sauté the shredded zucchini for at least 7 minutes or until there is no more liquid in the pan.
Tweak it! While this tart tastes fantastic as is, feel free to add sautéed mushrooms, green peas, or even bell peppers to the batter for more texture and flavor!