½ cup warm water (no more than 100 degrees F/40 degrees C)
2 teaspoons active dry yeast
1 ½ cups cake flour
½ cup cornmeal
⅓ cup superfine sugar
½ teaspoon salt
½ cup milk
⅓ cup melted butter
1 egg
¼ teaspoon vanilla extract
¼ cup raisins (Optional)
Pour warm water into a small bowl, then sprinkle yeast over the surface. Let stand until yeast softens and begins to form a creamy foam, about 5 minutes.
Sift cake flour, cornmeal, sugar, and salt together in a small bowl.
Beat milk, melted butter, egg, and vanilla in a large bowl until smooth. Stir in flour mixture until just combined. Stir in yeast mixture until smooth. Cover with a light cloth and let rise in a warm place until doubled in volume, 1 to 2 hours.
Line a 9-inch round pan with parchment paper. Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Cover and bring to a boil over high heat.
Pour risen batter into the prepared pan and sprinkle with raisins. Place the pan onto the steamer insert. Cover the pan and steam until a toothpick inserted into the center comes out clean, about 25 minutes.
Transfer the pan to a wire rack to cool for 10 minutes, then remove cake and place directly onto the wire rack to cool completely.
