Pre-heat oven to 150C.
Double sift rice flour together with the baking powder and salt. Set aside.
Add yolks and mix lightly with a hand whisk until just combined.
Combine the milk and oil and warm for 15-20 seconds in the microwave.
Add the sifted flour mixture in 2 to 3 parts, alternating with the warm milk. Mix until just combined. (The warm milk helps the eggs to aerate and keeps the batter light and airy). Set aside and whip the meringue.
Beat egg whites until foamy. Add the granulated sugar in 3 parts and beat till soft peaks.
Add 1/3 of the meringue into the yolk mixture to and whisk gently to loosen it. Once it is combined, add the yolk mixture together with 1 tsp vanilla extract to the rest of the meringue and lightly mix.
Switch to a spatula and mix gently until the batter is even and well combined. Be careful to fold gently and slowly so as not to deflate the air that has been whisked into the batter.
Line the base of a 6 x 3 inch round cake tin and pour in the cake batter. Tap the cake tin a few times on the work table. Then, gently run through the batter with a wooden skewer. Both the tapping and stirring with a skewer will help to remove large air bubbles.
Once the oven is pre-heated to 150C, bake at the lowest rack of the oven for 40 minutes or until a skewer comes out clean. Set the cake aside to cool completely before unmoulding.