Reduce oven temperature to 340F (170C). Grease and line the bottom and sides of a 8 inch (20 cm) pan with parchment paper.
Separate whites from yolks.
In a medium bowl mix yolks with 1/3 cup (70g) sugar and vanilla extract, until creamy and pale yellow colored. Gradually mix in oil and then add sparkling water.
In a large bowl mix egg whites with salt until foamy. Gradually add remaining 1/3 cup sugar (70g).
Continue mixing until stiff peaks form.
Gently fold a spoon of whipped whites into the yolk mixture and then gently fold the yolk mixture into the whipped whites.
Gradually sift the flour and baking powder over the egg mixture and gently fold them in.
Pour the batter into the prepared pan.
Bake for 35-40 minutes, until a toothpick inserted into the center comes out clean.
Let it cool for about 10-15 minutes. Remove from the pan and cool completely on a rack.