1. Firstly, in a large mixing bowl soak 1 cup idli rice for 5 hours. if you do not have idli rice, then can use sona masuri rice.
2. Drain off the water and transfer to a mixy jar along with ¼ cup grated coconut.
3. Add water as required and blend to slightly smooth paste. make sure the batter is not too smooth. the batter must be little coarse but not too coarse too.
4. Take 2 tbsp of prepared batter and pour over pan along with ½ cup water. make sure the flame is off.
5. Mix well making sure the batter combines well with water.
6. Now turn on the stove on medium flame and keep stirring. transfer the prepared cooked batter into appam batter. mix well making sure there are no lumps.
7. Cover and ferment in warm place for 8 hours or till the batter ferments well.
8. After 8-10 hours, mix the batter gently and check for consistency. add in ½ tsp sugar, ½ tsp salt and pinch of baking soda.
9. Heat appam pan or appachatti over medium flame and pour a ladleful of batter into the pan.
10. Immediately twirl the pan to spread the batter in a circular motion.
11. Further cover and simmer for about 2 minutes or until the edges turn golden brown and gets cooked completely.
12. Finally, carefully remove the palappam / appam from the pan and serve with vegetable curry.