Prepare Potato Filling: Heat 1 tablespoon of oil in a pan. Add mustard seeds and let them splutter. Add asafoetida, curry leaves, ginger-garlic paste, and green chilies. Sauté for one minute until fragrant.

Add the mashed potatoes, turmeric powder, and salt. Mix well to combine all ingredients. Cook for 2-3 minutes, stirring occasionally.

Stir in the chopped cilantro and lemon juice. Remove from heat and let the mixture cool slightly. Once cool enough to handle, form the potato mixture into small, golf-ball-sized balls or flattened patties.

Prepare Batter: In a separate mixing bowl, combine chickpea flour, rice flour, red chili powder, baking soda (if using), and a pinch of salt. Gradually add water, whisking continuously, to form a smooth, thick batter without any lumps. The batter should be thick enough to coat the back of a spoon.

Fry Batata Vada: Heat the remaining oil for deep frying in a Kadai or deep pan over medium-high heat. To test if the oil is hot enough, drop a tiny bit of batter; it should sizzle and rise immediately.

Dip each potato ball completely into the chickpea batter, ensuring it is evenly coated on all sides.

Carefully slide the coated potato balls into the hot oil. Fry 3-4 at a time to avoid overcrowding the pan, which can lower the oil temperature.

Fry until the Batata Vadas are golden brown and crispy on all sides, turning them occasionally to ensure even cooking. This usually takes 3-5 minutes per batch.

Remove the fried Batata Vadas from the oil using a slotted spoon and place them on a plate lined with paper towels to drain any excess oil.

Serve the Batata Vada hot immediately with your favorite green chutney, tamarind chutney, or as part of a classic Vada Pav.