In a big bowl, sift together the flour, sugar, baking powder and salt. Pour on top the egg yolks, oil, cold water, and vanilla, and like that, without stiring at all, set aside.
In another, clean and dry big bowl, using a mixer, beat the egg whites until they rise and start to turn whitish.
Using a rubber spatula, carefully incorporate the egg whites to the main mixture, in three different additions, until it is all well mixed, making sure the mixture doesn´t lose air.
Pour the mixture into a non-greased removable bundt cake mold and bake at 325°F (160°C) for about an hour or until a wooden stick comes out clean when inserted.
Once ready take out of the oven and let it cool down placing the mold upside down so that the cake doesn´t shrink. You can do this using a bottle of wine, placing the center of the mold on the tip of the bottle.
Once completely cool, turn it out using a knife if needed and serve.