Place quinoa in a small bowl and cover it with several inches of water. Let it soak at room temperature for 8 hours or overnight. Alternatively, skip soaking and rinse it. See the notes on the main differences between the soak and no-soak results.
Cut a piece of parchment paper to cover a pizza pan or pizza stone. Set the paper aside and add the pan to the oven as you preheat it to 425 F (220 C).
Rinse the quinoa (drain first if it's been soaked). Then add all the ingredients to a blender or food processor.
Start blending at a slow speed, gradually increasing as the quinoa breaks down. Scrape the sides and bottom a few times to pick up individual quinoa grains.
Remove the heated pizza pan and lay the parchment paper on it.
Pour the quinoa batter into the middle of the paper and use a spoon or spatula to spread it to the approximate size of a 15-inch pizza (about ¼ inch thick).
Place the crust in the oven and bake for 15-18 minutes until it starts to firm and brown.
Remove the crust from the oven, slide the paper from underneath the crust, add your favorite toppings, and return to the oven. Bake another 10-15 minutes.
If you are making a salad pizza or freezing the crust, you'll need to flip it. To do this, slice a cutting board or some flat over the top and flip the pizza pan over. Peel the parchment paper off and slide the crust, baked side down, onto the pizza pan. Bake for another 10 minutes to brown it.