Step 1: Preparation
1-Preheat the oven to 150°C (top and: Preheat the oven to 150°C (top and bottom heat).
2-Prepare two clean, dry bowls-one for the: Prepare two clean, dry bowls-one for the egg whites and one for the egg yolks. Ensure they are free of oil and water to prevent any interference with the egg white whipping process.
3-Separate the eggs, placing the whites in: Separate the eggs, placing the whites in one bowl and the yolks in another. To make the egg whites easier to whip later, place the bowl of egg whites in the freezer for 10 minutes.

Step 2: Make the Egg Yolk Batter
4-In a separate bowl, combine 40g corn: In a separate bowl, combine 40g corn oil and 60g milk, whisking until emulsified.
5-Sift 60g cake flour into the milk: Sift 60g cake flour into the milk and oil mixture, stirring until there are no lumps or dry spots.
6-Add the egg yolks to the batter: Add the egg yolks to the batter and gently fold with a spatula in a “Z” motion until the batter becomes smooth and glossy. Set aside.

Step 3: Whip the Egg Whites
7-Remove the egg whites from the freezer: Remove the egg whites from the freezer and add 3g lemon juice to help stabilize the meringue.
8-Using an electric mixer, whip the egg: Using an electric mixer, whip the egg whites on high speed for about 50 seconds until they form large bubbles.
9-Gradually add 50g white sugar in three: Gradually add 50g white sugar in three portions: After the first addition, whip until large bubbles form. Add the second portion and whip until the bubbles become finer. Add the final portion of sugar and continue to whip until soft peaks form, where the egg whites curve slightly when the whisk is lifted.

Step 4: Combine the Batter
10-Gently fold 1/3 of the whipped egg: Gently fold 1/3 of the whipped egg whites into the egg yolk batter using a spatula. Fold carefully, ensuring you don’t deflate the mixture.
11-Once incorporated, add the remaining egg whites: Once incorporated, add the remaining egg whites to the mixture and gently fold until the batter is smooth and fully combined. Avoid overmixing to preserve the airiness of the batter.

Step 5: Baking
12-Line a baking tray with parchment paper: Line a baking tray with parchment paper. Pour the batter onto the tray and use a spatula to spread it evenly, ensuring the surface is smooth.
13-Tap the tray gently on the counter: Tap the tray gently on the counter to release any air bubbles.
14-Place the tray into the preheated oven: Place the tray into the preheated oven and bake at 150°C for 20 minutes. After that, increase the top heat to 160°C while keeping the bottom heat at 150°C, and bake for an additional 10 minutes until the cake is golden brown and springs back when lightly pressed.

Step 6: Rolling the Cake
15-Once baked, carefully remove the cake from: Once baked, carefully remove the cake from the oven and place it on a cooling rack. Let it cool until it’s warm to the touch.
16-Place a sheet of parchment paper on: Place a sheet of parchment paper on top of the cake, then flip it over so that the parchment paper is underneath. Carefully peel off the parchment paper that lined the cake during baking.
17-While the cake is still warm and: While the cake is still warm and flexible, place a rolling pin at the edge of the cake. Gently start rolling the cake with the help of the parchment paper. Pull the parchment paper back as you roll to keep it out of the way.
18-Once the cake is fully rolled, use: Once the cake is fully rolled, use a spatula to tighten the roll and make sure it holds its shape. Let the cake set for 30 minutes.

Step 7: Slice and Serve
19-After the cake has set, slice it: After the cake has set, slice it into even pieces and serve. Enjoy the light and airy texture of this delicious Chinese Swiss Roll!