Preheat steamer while you prepare.
Line a six-inch round bamboo basket with parchment paper.
In large bowl, sift together All-Purpose Flour (175 gram), Cake Flour (175 gram), Baking Powder (1 tablespoon), and Salt (1/4 teaspoon).
In your mixing bowl, whisk Egg (3), Caster Sugar (185 gram), and Cake Stabilizer (1 teaspoon) together on high speed for ten minutes.
Mix until pale and fluffy.
Turn your mixer down to low and drizzle Vanilla Extract (1 teaspoon) and Water (170 gram).
Lastly, gradually fold in dry ingredients.
Transfer into your lined basket, and gently drop the pan against the worktop to get large air bubbles out.
Place it in the steamer for thirty five to forty minutes over rapidly boiling water.
Let it cool for 20 minutes before serving.