For the dough: Mix the dry ingredients in a large bowl. Add the oil and water and mix well until the dough gathers into a ball, adding a little extra flour if it is sticky or a drizzle of water if dry. Knead for about 5 minutes until it becomes smooth and pliable. Lightly oil the bowl and turn the round dough over to coat. Cover with plastic wrap and let rest in a warm place for at least 2 hours.
For the sauce: In a medium saucepan heat the oil over medium heat and sauté the onions and garlic for 3-5 minutes. Add the tomato sauce, salt and pepper and bring to a boil. Mix in the oregano and cook for 5 minutes. Set aside to cool.
Line 2 large baking sheets with parchment paper. Divide the dough in two equal parts. Roll out half of the dough on a lightly floured surface to 2 mm thickness. Carefully transfer onto the prepared sheet. Spread with half of the tomato sauce. Cover with half of the topping’s ingredients.
Preheat oven (220°C, 425°F). Bake for about 20 minutes.