Old-Fashioned Sponge Cake (Original)

📜 Ingredients Eggs: 3 (yolks and whites must be perfectly separated; the bowl for egg whites must be absolutely free of water and oil) Vegetable oil: 35g (light-flavored salad oil, canola oil, or corn oil recommended) Cake flour: 50g (must be sifted) Whole milk: 40g Granulated sugar: 40g Lemon juice: A few drops (for stabilizing egg white foam; white vinegar can be substituted) 📖 Simple Steps Making the Yolk Batter (Scalded Flour Method) 1. Heat the oil: Pour the oil into a small pot and heat over low heat until slightly warm and the surface shows faint patterns (about 70-80°C), then immediately remove from heat. (Alternatively, microwave on high for about 40 seconds). 2. Mix the scalded flour: Immediately add the sifted cake flour and quickly whisk into a smooth batter with no lumps. 3. Add liquids: Pour in the cold milk and mix well. 4. Add yolks: After the batter has cooled slightly, add the 3 egg yolks in portions, mixing well to create a smooth, flowing yolk batter. Making the Fine Meringue 1. Add acid and whip: Add a few drops of lemon juice to the egg white bowl and whip on high speed with an electric mixer. 2. Add sugar in portions: Add the sugar to the egg whites in 3 additions. Add the first portion when the egg whites change from large bubbles to fine small bubbles; the second when streaks begin to appear; and the last portion when it reaches a wet foam stage. 3. Whip to soft peaks: Finally, switch to medium-low speed and whip until the meringue forms soft peaks that curve slightly when the whisk is lifted (a stage between wet and firm peaks).