Wash and soak the raw rice in water for 3-4 hours till it becomes soft enough to grind .
Take yeast and sugar in a bowl and pour the lukewarm water into it and keep aside.
Make sure the water is not too hot or else, the yeast will die.To check, pour a little water on the inside of your wrist.If it is bearable, then the temperature is fine.It takes about 10 minutes for the yeast to act.
Transfer the raw as well as cooked rice into a grinder.Add the grated coconut (if using), yeast and the required amount of water to get a medium thick finely ground batter.Transfer to a utensil.Cover with lid and keep in a warm place to rise.
When the batter has risen, add a tablespoonful or more of sugar and mix well.If the batter is too thick, add some coconut milk or milk to dilute it a bit.Heat the appachatti.
When hot, add a spoonful of the batter. Swirl it either to form a round shape or floral shape (as shown in the picture).
Let the remaining batter be the in the centre.Cover and cook on medium low heat.
Touch the centre to see if it is cooked. If it sticks to your finger, allow to cook further.
Take off the appam and serve hot.Repeat the process till the entire batter is used up..