Add water to make a thick batter (just like idli batter consistency).
Cover and let it rest for some time (15 - 20 minutes).
After said duration, check the batter.
Add some more water if it's thicker.
Now heat oil in a tadka pan.
Add mustard seeds, cumin seeds and let it crackle.
Add chopped onions, ginger, green chillies and saute for a minute.
Now remove the pan from heat.
Pour in the tempering to the batter.
Whisk it well in one direction for 2 - 3 minutes.
Now divide it into 2 portions.
Take out one part and add half tsp fruit salt or soda.
Mix well.
Take appe pan and grease the sockets with little oil.
Heat the pan.
Pour in 1 tbsp batter into each socket of the pan.
Cover with a lid and cook on low flame for 2 minutes.
Now take a spoon and flip all with the help of a spoon.
Sprinkle little oil on them.
Again cover and cook for another 2 - 3 minutes.
Remove from pan when done golden on both sides.
Repeat for other batch of batter.
Serve as snack or breakfast or pack for your kid's tiffin box.
Serve with any chutney of your choice.
Notes
Add soda or eno just before pouring the batter into appe pan. Thats why I have divided the batter into batches. Otherwise eno will have no effect for 2nd batch and so on.