Soak rice for 4 hours, then grind with grated coconut and water to a fine batter.
Dissolve yeast and sugar in 2 tbsp warm water, stir into batter, and ferment overnight.
Add salt and adjust consistency so batter is thin and pourable.
Heat an appam pan, pour a ladle of batter, and swirl the pan to spread thin edges.
Cover and cook on medium heat for 2 minutes until center is fluffy and edges are crispy.