Soak washed rice for about 4 hrs in cold water , Then wash well, drain and keep aside.
Soak yeast with 3 tbsp luke warm water and 1 tsp sugar and keep aside.
from the soaked rice take 2 tbsp rice and grind it in to a coarse powder (consistency of put powder)
in a sauce pan add 1 cup water and mix the rice powder in to it.bring it to boil over medium flame .Stir continuously until you get a porridge consistency. switch off the stove and keep it aside to cool. this is locally called kappi kachuka.
Then add half of the coconut in to a blender add 1/4-1/2 cup lukewarm water. blend well then extract coconut milk and keep it aside.Once the kappi become cool add this to the coconut milk mix well and keep aside.
Then Add soaked rice and remaining coconut, into a blender. Add one cup coconut water or normal water in to it (be careful while adding water as the batter should not become too watery). then grind well in to a smooth batter
Transfer the batter into a large bowl . Add yeast , sugar and salt,coconut milk and kappi mix.Then mix well together.cover this with a lid and keep it in a warm place for 5-6 hours to ferment.once fermented add cardamom powder and gently mix.
then grease a stainless steel plate or flat plate or idly mold with little oil. Then spoon in the fermented batter to the plate. (if you prefer garnish with raisins and cashews.)Steam cook for 15 to 20 minutes.