Step 1

Transfer 1/4 cup water to a cup or bowl. Microwave the water on High power for 10 seconds. (Water temperature should be 100-110 F (38-43 C)). Add the active dry yeast along with 1/2 tsp sugar. Stir to moisten the yeast. Let the mixture rest for 10 minutes or until foamy.

Step 2

Transfer the rice flour into a medium bowl. Add 3/4 cup water and combine together until smooth. (The mixture will be thick.)

Step 3

Add sugar to the remaining 1 cup water and combine together. Microwave the mixture on High powder for 45 seconds. Stir together dissolving the sugar. (Liquid temperature should be 100-110 F (38-43 C)).

Step 4

Add the yeast and sugar mixtures to the rice flour mixture. Stir the batter, combining all ingredients well. Cover the batter bowl with plastic wrap. Transfer the bowl into a microwave or oven. Place 2 cups boiling water next to the bowl to generate heat. Close the door and let the batter rest for 1 1/2 - 2 hours or until large bubbles form on the surface. Stir the batter again, mixing well.

Step 5

Coat the inside of a 9 inch round cake pan with vegetable oil. Place the cake pan inside the steamer tray. Fill a steamer basin halfway with water. Cover and bring to a rapid boil over High heat.

Step 6

Reduce the heat to Medium. Add the steamer tray with the cake pan. Stir the batter a few more times and then pour into the cake pan. Skim off any large bubbles from the top of the batter.

Step 7

Wrap a kitchen towel around the lid and place the lid on the steamer. Steam the cake for 25-30 minutes. Test the cake for doneness by inserting a toothpick into the cake and it should not have any wet batter sticking to it.

Step 8

Turn off the heat and let the cake rest in the steamer (lid off) for 10 minutes.

Step 9

Remove the cake from the steamer and let cool on the counter for another 10 minutes.

Step 10

Use a spatula to loosen the cake from the sides of the pan and then transfer the cake to a large plate.

Step 11

Cut the cake into slices and enjoy as finger-food.

Step 12

Cover and store the White Sugar Sponge Cake at room temperature for up to 24 hours. Afterwards, refrigerate for up to 4 days. To reheat, warm in the microwave or by gently steaming.