Mix Chana Besan, turmeric powder, chilli powder, asafoetida & salt in a bowl.
Pour water to the mixture as required and whisk it all together.
Add coriander to mixture and mix well.
Heat the pan on medium flame.
Once hot, pour a ladleful of batter on it and spread it in circular motion.
Smear 1 tsp of oil all over it and along the edges.
Cook the chilla on low flame until it turns golden brown and crisp.
Flip it around and cook it another minute on low flame.
Fold it to a semi-circle and take it off the pan, placing it in on a plate to serve.
Repeat step 5, 6, 7, 8 to prepare the rest of the chillas.
Serve them hot with ketchup and / or green chutney.