Sift cake flour, baking powder and salt together a couple of times.
Separate egg whites and yolks.
In a bowl of stand mixer, beat yolks 1/4 cup sugar, vanilla, water and oil together for a minute. Add flour mixture and whip at high speed for a minute. Set aside.
In a clean bowl, beat egg whites adding 1/2 cup sugar in 3 parts until medium to hard peak.
Fold in 1/4 meringue to yolk mixture. Then add rest of meringue and mix, taking care not to deflate foam.
Pour the cake batter into the bowl of the rice cooker. If your cooker has a Cake mode, use that and follow the appliance’s instructions.
If it doesn’t, cook the batter using the regular white-rice setting. When the cycle finishes, run the same setting once more.If the cooker won’t start a second cycle right away, close the lid and let it rest for about 15 minutes to cool down the cooker slightly, then start the cycle again.
Turn the bowl up side down on a cooling rack. No need to remove the cake at this point. When cooled completely, remove the cake from the bowl.
Slice a cake and serve with whipped cream and berries.