Peel and slice the bananas, then mix with sugar and yeast. Blend until smooth. In a separate bowl, mix water with rice flour and salt, then combine with the banana mixture.

Cover the mixture and let it rest for about 2 hours to rise. Bring water to a boil in a steamer, grease the steamer tray, and preheat. Pour the batter into the tray and steam for about 30 minutes until the cake is cooked through.

Remove the cake and let it cool, then cut into pieces. Squeeze the coconut to get about 3 cups of coconut milk. Take out 1/2 cup and mix with 1 tablespoon rice flour and 1 tablespoon tapioca starch. Add 1 tablespoon sugar and 1/3 teaspoon salt to the coconut milk, bring to a boil, then slowly add the flour mixture, stirring until it thickens to your desired consistency.

Once the sauce is cooked, remove from heat and add chopped green onion.

Serve the banana rice cake with the coconut sauce and green onion for a delicious treat.