Steps

1. Separate the eggs into whites and yolks. Place the egg whites in a large bowl and keep them chilled in the refrigerator until ready to use. Preheat your oven to 170℃ (340℉). [Key Tip!] Chilled egg whites whip up better.
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2. Lightly beat the egg yolks and mix in 20g of the granulated sugar quickly. [Key Tip!] Granulated sugar can absorb moisture from the egg yolks, so mix it in immediately after adding to avoid any grainy texture.
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3. Add 40ml of vegetable oil to the beaten egg yolks and mix well to prevent separation. Next, add 60g of plain yogurt and mix thoroughly.
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4. Sift in 60g of all-purpose flour and gently mix until just combined, being careful not to scatter it.
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5. Whip the chilled egg whites with a hand mixer on high speed for 30 seconds to create coarse bubbles.
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6. Add all of the remaining 40g of granulated sugar to the egg whites. Whip with a hand mixer on high speed for 1 minute 20 seconds until stiff peaks form. [Key Tip!] The whipping time may vary depending on your hand mixer, so whip until stiff peaks form.
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7. Switch the hand mixer to low speed and whip for 1 minute to achieve a fine meringue texture.
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8. Add 1/3 of the meringue to the egg yolk mixture and mix thoroughly to combine the batters. [Key Tip!] Mix well the first time to incorporate both batters evenly.
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9. Add another 1/3 of the meringue and gently fold it in. Mix by lifting the batter from the bottom of the bowl and turning the bowl.
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10. Transfer the remaining egg yolk mixture into the bowl with the meringue. Switch to a rubber spatula and gently fold until just combined. If there are lumps of meringue, gently cut through them with the spatula to avoid uneven mixing. [Key Tip!] Transferring the egg yolk mixture to the meringue bowl helps prevent uneven mixing.
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11. Pour the batter into the chiffon cake pan, dividing it equally into four sections.
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12. Drop the pan from a slight height 2-3 times and swirl with a skewer to remove any large air bubbles.
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13. Place the pan on a baking sheet and bake in the preheated 170℃ (340℉) oven for the first 7-10 minutes, just until the surface is set.
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14. Remove from the oven, make four cuts into the surface, and return to the 170℃ (340℉) oven to bake for another 23 minutes (total baking time: 30 minutes). [Key Tip!] Making cuts during baking helps the cake puff up beautifully.
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15. Immediately after baking, invert the cake by placing it onto a bottle or stand and let it cool completely. [Key Tip!] Inverting the cake right after baking prevents it from collapsing and ensures a fluffy texture.
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16. Once the chiffon cake has cooled, carefully peel away the parchment paper from the sides of the pan. Gently separate the bottom of the cake from the pan. Remove the center tube and your cake is ready.
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17. Slice into your desired portions and enjoy.
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