Preheat oven to 200 degrees celcius° and line a 13×9 baking sheet with parchment paper
1. Add the zucchini and onion to a colander and sprinkle with the salt. Toss it well. Weigh the vegetables down with a plate or other clean, heavy object. Place in the sink or bowl to allow the excess water from the vegetable drain away.
2. In the meantime, add the rice flour, cornmeal, parmesan, oregano and garlic powder to a bowl and mix to combine. Add the olive oil, eggs and about ¼ cup of water to make a thick batter.
3. Squeeze as much water out of the zucchini and red onion as possible. Add them to the batter. Stir the vegetables into the batter until everything is well coated. The mixture will be thick.
4. Drizzle the prepared baking sheet with the remaining olive oil. Scoop the zucchini batter onto the prepared pan and pat the batter down so it fills the pan to the edges.
5. Bake on the middle rack for 35-45 minutes or until brown and crispy.