In a bowl, whisk together gram flour, rice flour, turmeric, ajwain, salt, and a pinch of hing. 

Add water gradually to make a smooth, slightly thick batter.

Now, add baking soda and mix well.

Heat up oil in a deep pan for frying over medium heat until it hits about 180°C. 

You can test if it’s ready by dropping in a little batter. If it rises right away, you’re good to go.

Dip each potato ball into the batter, making sure it’s evenly coated, and then gently drop them into the hot oil. 

Fry them in batches until they’re golden brown and crispy. 

Once they’re done, drain them on paper towels to remove excess oil.

Finally, serve hot and enjoy batata vada with any chutney of your choice.