Combine cake flour, sugar, black sesame seeds, salt, and baking powder in a bowl. Stir 3–4 times with a whisk.

Mix water and vegetable oil together in a separate bowl.

Add the oil-water mixture to the dry ingredients and mix with a spatula until a dough forms.

Place the dough in a plastic wrap and roll it out evenly with a rolling pin.

Score the dough diagonally with a knife while still wrapped in plastic. Freeze for at least 30 minutes.

Place the dough on parchment paper and microwave for 2 minutes 30 seconds using the defrost setting (700W). Adjust time based on your microwave's wattage.