1. Prepare two containers to ensure that they are clean, dry and free of water. Sift the flour and corn starch and put them in a container.

2. Heat the oil to about 70 degrees. Pour the oil into the flour mixture and stir well.

3. Add milk and mix well. There may be oil leakage at this time, so don't worry.

4. Separate the egg whites from the egg yolks, put the egg whites into another container, and add the egg yolks into the mixture and stir evenly for later use, as shown in the figure. If there is lemon, you can squeeze a few drops at this time.

5. Send protein. Add sugar three times in the sending process, and send it to the picture. Don't go back soon after you pull it up, or you can turn the basin upside down. The egg white won't fall off, so it's ok. It's very important to send it, but it won't work after it.

6. Preheat the oven to 155 to 160 degrees. First, put one-third of the egg white into the yolk batter (because it may be uneven if poured too much at a time), as shown in the figure. Never stir with a wreath, it will affect the expansion of the cake. After stirring well, pour in one third of the beaten egg whites and stir again.

7. After stirring well, pour the mixed batter into the remaining beaten egg whites and stir well in the same way.

8. Put warm water in the bottom tray. Pour the prepared batter into the mold, then shake it to shake out the big bubbles in the batter. Put the mold on the top of the water tray, not on the middle or top of the oven, because the skin will dry out and the middle of the cake may be immature. Bake for about an hour.