Take gram flour, buttermilk, yogurt (add 1 cup water and stir well), turmeric powder, and salt in a bowl. Mix and make a smooth batter using a hand blender or a whisk.
On a low flame, cook the batter in a heavy-bottomed pan and keep stirring to avoid lump formation.
Meanwhile, grease a large plate or the back of a thali with cooking oil and keep it aside.
Cook until the batter becomes thick and until the raw taste is gone.
Transfer the cooked batter to the previously greased thali. Spread the batter in a thin layer with the back of a spoon or spatula.
Depending upon the quantity of batter, spread the whole batter on a large plate or 2-3 thalis.
Let it cool for a while and then place straight cuts using a knife and prepare wide strips.
Now carefully and lightly roll each strip into a roll and transfer them to a plate.
Heat 1-2 tbsp of oil in a small pan, add mustard and cumin seeds and let them crackle.
Add curry leaves and chopped green chili as they crackle, and saute them for a minute. Once cooked, add sesame seeds and turn off the flame.
Pour the seasoning over the rolled khandvi. And sprinkle coriander leaves as Garnishing.
Serve the Khandvi rolls with mint coriander chutney or garlic chutney.