Divide egg whites from the yolks. In a bowl mix the oil, the water, the yolks, the grated orange peel, and the juice. Start whipping the egg whites with a pinch of salt and halfway, add some cream of tartar (it will help to keep the result firmer). Preheat the oven at 160°. Put all the powdered ingredients (flour, baking powder, and sugar) in a different bowl and mix them.