Whisk the oil and the condensed milk until incorporated, add in egg yolks, mix well, then sift in cake flour, mix well.
In a clean bowl, add in egg white, lemon juice, vanilla extract and sugar, beat until soft peaks form, take ⅓ of the meringue, fold in to the batter, then pour the batter back to the rest of the meringue, fold it in until just combined.
Preheat the oven to 110℃(230℉). Line a 12-cup muffin tin with paper liners. Pour the batter into the prepared muffin cups, filling each ¾ full. Give it several taps and use a toothpick to remove large bubbles.
Bake on 110℃(230℉) for 20 minutes, then 130℃(266℉) for 30 minutes, finally 145℃(293℉) for 5-6 minutes.
Cool and serve.
