Combine yeast, ¼ teaspoon sugar, and 1 tablespoon water, and leave it to ferment for about 10- 15 minutes.
Meanwhile, grind rice, coconut, cooked rice, & water together to make a smooth, thick batter. Add in yeast, ½ cup sugar, and ground cardamom and cumin seeds. Mix well. Again, leave the batter in a warm place to ferment for 7 -8 hours.
When the batter is ready, you can transfer it to an idli or vattayappam mould greased with oil. Decorate with cashews & raisins. Steam it for 15-20 minutes. When cooked, allow it to cool. Then slice and serve.