Boil the potatoes in a pressure cooker or pot of water until a knife slides through them easily, then drain and let them cool enough to handle.

Peel the boiled potatoes and mash them coarsely in a bowl, leaving a few small chunks for texture rather than a completely smooth mash.

Heat a little oil in a pan, add the mustard seeds and let them sputter, then add the curry leaves, chopped onion, green chili, and ginger and sauté until the onion turns translucent.

Add the turmeric and salt to the tempering, then fold in the mashed potato, chopped coriander leaves, and lemon juice until evenly combined.

Divide the potato mixture into equal portions and roll each one between your palms into a smooth, crack-free ball about the size of a golf ball.

Whisk the gram flour, red chili powder, baking soda, and salt with enough water to form a smooth, coating-consistency batter with no lumps.

Let the batter sit so the gram flour fully hydrates and the baking soda starts working, giving a lighter, crisper crust once fried.

Heat the oil in a kadai over medium heat until a small drop of batter dropped in rises to the surface immediately with steady bubbling.

Dip each potato ball fully in the batter, let the excess drip off, and slide it into the hot oil, frying in a single uncrowded batch until deep golden brown all over.

Repeat the dipping and frying process with the remaining potato balls, letting the oil return to temperature between batches so each one fries evenly.

Lift the fried bondas out with a slotted spoon onto a plate lined with paper towels and let them sit briefly so the excess oil drains off and the crust sets.