Take a sauce pan and add curd and water to it and mix it well.
Add green chilli paste, turmeric powder and asafoetida to it.
Add besan little by little and mix it well. Add salt according to taste.
Blend into a lump free mixture using a hand blender.
Take a heavy bottom pan and add the mixture to it. Keep on stirring the mixture continuously on a low flame.
After around 10 minutes you will see that the mixture is thickened like a paste.
You can test by spreading a little mixture as a thin layer on a flat surface like a thali and allow it to cool for 2 minutes. If you can roll it easily then switch off the flame.
Quickly spread the thin layer of mixture on flat surfaces using a spatula. Allow it to cool for 10 minutes. You can use both sides if the surface is flat.
Make a 1 inch wide cuts on the layered mixture in thali and start rolling from one side in a tight roll. Add all the rolls on a serving plate.
Heat oil in a pan and add mustard seeds and curry leaves to it. Once they crackle add sesame seeds in it and turn off the flame. Spread the tadka over the rolls.
Garnish with freshly grated coconut and coriander leaves.