Refrigerate whole eggs for 30 minutes before use.

Carefully separate egg yolks and whites (make sure no yolk gets into the whites). Place whites into a clean, grease-free bowl and refrigerate.

Preheat oven to 140°C (top and bottom heat) for 10 minutes. Line a cupcake pan with mini cupcake liners.

In a mixing bowl, combine 50g milk and 45g corn oil. Use a whisk to stir in circular motions for 1–2 minutes until fully emulsified—mixture should look like yogurt (no oil separation).

Add 4 egg yolks and whisk until the mixture is smooth and glossy.

Sift in 70g cake flour and fold using a “Z” motion with a spatula until no dry flour remains. Batter should be smooth and flowy but have a bit of resistance.

Tip: Do not overmix or the gluten will develop and cause collapse.

Take egg whites from the fridge, add 3–5 drops of lemon juice or vinegar.

Beat on low speed until large bubbles appear (~20 seconds).

Add 30g sugar, increase to medium-high speed and whip until small, uniform bubbles form (~1 min).

Add remaining 30g sugar and 5g cornstarch, continue beating until the meringue forms stiff peaks—it should hold its shape with a straight tip when you lift the whisk.

Tip: Proper meringue will not slide if you turn the bowl upside down.

Scoop 1/3 of the meringue into the yolk batter. Use folding motion from bottom to top (like stir-frying), mixing quickly (~15 strokes) until combined.

Pour the mixture back into the rest of the meringue. Use a folding and cutting motion—cut through the middle, scoop under and fold over—until fully combined.

Important: Do not stir in circles. Keep total folding under 30 strokes to avoid deflation.

Transfer batter into a piping bag (no tip needed), snip a 1cm opening. Pipe into mini cupcake liners up to 80% full (about 2/3 height).

Tap tray 2–3 times to release big air bubbles. Optionally, sprinkle black sesame seeds on top.

Bake on the middle rack at 140°C for 45 minutes (for mini cupcakes).

Done when surface springs back when touched and toothpick comes out clean.