Preheat an oven to 210℃ / 410 F. Separate the egg yolk from the egg white. Put the egg yolks in a large bowl. Put the egg whites in another large bowl and chill in a fridge. Put the milk in a small bowl. Place the small bowl in around 50℃ / 122 F hot water to warm the milk; set aside. If you mix water and boiling water in the same ratio, it reaches about 50℃ / 122 F.

Add 1 Tbsp granulated sugar to the egg yolk. Use a whisk to beat for 1 minute.

With stirring, drizzle oil little by little over. After adding all, stir for another 1 minute.

With stirring, drizzle the warm milk little by little over. After adding all, stir for another 1 minute.

Sift cake flour and bread flour over. Stir it until smooth, and then beat speedy 30 times. Set aside.

Take the egg white out from the fridge. Use an electric hand mixer to beat on high speed. When it turns dark white, add half the granulated sugar. Beat for another 1 minute until heavy, and add the other half of sugar and beat.

Beat it until stiff peaks form. The tip should hang down lightly. Beat slowly on low speed for a min to smooth it.

Add the meringue to the egg yolk batter in 3 parts. 1st addition, use a whisk to stir well until smooth.

2nd and 3rd addition, use a spatula to fold it into the cake batter while scooping carefully and gently until you don’t see the big chunk of meringue left.

Next, use a whisk to scoop it up and let it slip through your whisk. Repeat until smooth 30-50 times.

Finally, use a clean spatula to scrape off the batter from the edge or bottom and fold it 10 times. The batter should be heavy and glossy.

Pour the batter into an ungreased tube pan. Stir it with a bamboo skewer to flatten. Hold down the top of the tube and drop it lightly 2-3 times to remove large bubbles. Lower the oven to 180℃ / 356 F and bake for 30 minutes.

Upside it down immediately. Let it sit as it is for 4 hours or more to cool completely. (If possible, wrap it with a plastic bag to seal it, and put it in a fridge overnight. You can remove the cake from the pan cleanly.)

Remove the cake from the pan. Use your hands to press gently the edge and center (around the tube) to press down the cake until half the height.

Upside down, hold down the bottom plate and lift the side to push the cake out. Next, gently press the outside of the cake to peel it off from the bottom.

It's all done! It tastes good fluffy and moist.