Arrange some steel plates to spread the batter. You can also spread the batter on the counter top. Brush the plates with little oil.
In a bowl add besan, curd, water, sugar, turmeric powder, salt and mix together to make a lump free thin and smooth batter.
Transfer the batter to a non-stick pan and cook on medium heat. Keep stirring continuously for 8-10 minutes or till batter becomes thick.
Spread a teaspoon of batter on a plate. Try to roll it after few seconds. If you are able to roll it, then batter is cooked. If not, cook for another 2-3 minutes.
Once the batter has reached the desired consistency, immediately remove and spread on the greased plates evenly and as thin as possible using the back of spoon or spatula.
After 2-3 minutes, cut the besan layer into 1 or 2 inch strips. Then roll each strip tightly and place them on the serving dish.
Heat oil in a small pan and add mustard seeds. When it pops, add hing, red chilly, sesame, green chilly and curry leaves. Saute them for few seconds and pour over the rolls.
Garnish with grated coconut and coriander leaves.