Buy yeast to make fermented rice: crush 1 tablet and mix with 2 tablespoons cooked rice, then let it ferment for 4 days.

Mix the rice flour and tapioca starch. Add the fermented rice and knead until smooth, then add 3 tablespoons (50 g) water and knead again until the dough has the consistency of bánh ít dough. Cover and let rise for 8 hours.

Once the dough has risen, combine the remaining water with the cane sugar and a pinch of salt. Heat until the sugar dissolves, then let cool. Add this syrup to the dough (the dough should have risen before adding the syrup, making the total rise time about 10 hours). Add the syrup, then strain out any solids from the fermented rice. Let the batter rest overnight. When bubbles appear on the surface, it's ready to steam. Grease the molds and preheat them. Pour in the batter and steam for about 8 minutes. If a toothpick comes out clean, the cakes are done. Remove the cakes from the molds.