Preheat the oven to 170¬8C
Sift the flour 3 times with the baking Powder
whisk half the sugar with the egg yolks until thick tripled in volume and has reached the Ribbon Stage (you can draw a ribbon with the mixture when you lift the whisk up and the ribbon stays for about 30 seconds or more).
Add the Oil, Water and vanilla essence and whisk until the mixture is well combined.
Add the flour and baking powder and mix until well combined (Don't worry about folding it in)
In a large mixing bowl, whisk the egg whites (gradually adding the rest of the sugar) until stiff peaks have been formed and you can hold the bowl of egg whites over your head without any of the whites moving or falling on you.
Fold the egg whites in thirds into the yolk mixture using a spatula and then pour into the cake tin. (Do not grease the tin or line it with anything).
Bake for 50 minutes and as soon as it's done, take it out of the oven and flip it upside down to cool completely.