Firstly take a bowl and add in idly rice, urad dal, poha, fenugreek seeds. Clean them for 3 to 4 times and add in enough water and allow it to soak for 5 to 6 hours.
Then take a mixer jar and add in soaked above ingredients and then add in grated coconut. Then ground them into smooth batter.
Then close the lid and allow it to ferment it for 7 to 8 hours or overnight.
After fermentation add in salt to taste and sugar. Give a mix.
Later heat a pan and grease the pan with oil or ghee.
Then pour the ladder full of batter on pan and close the lid and cook for 1 minute in low flame.
Then remove the dosa from the pan.
Finally the sponge dosa is ready to serve with coconut chutney.