Cook the potatoes in a pot of boiling water until tender. Peel and mash the potatoes and place in a bowl.
Add chillies, ginger, turmeric, salt and lemon juice to potatoes. Mix to combine.
In a skillet, heat oil. Add mustard seeds. After 1 minute when they've started popping, add urad dal and chana dal. Fry until golden brown. Add curry leaves and fry for 1 more minute.
Add to potato mixture and stir to combine. Place in refrigerator for a few minutes while you get the batter together.
In a large bowl, combine chickpea flour, cumin seed, baking soda, salt and turmeric. Stir to combine. Add enough water to make a thick batter (I used 3/4 cup) and stir well.
Take potato mixture from refrigerator and form into 13 even sized balls.
Heat a deep skillet with enough oil for deep frying.
Dip each potato ball into the chickpea batter, making sure it is well coated on all sides. Place in the hot oil and fry until golden brown on all sides. Drain on paper towels.
Serve with your favorite chutney.