Cut each potato in half lengthwise, then cut each half into 3 or 4 even wedges so the pieces cook in similar time. No need to peel unless you prefer it.

Soak in cold water 20 to 30 minutes if you want an extra-crisp edge, then drain and pat completely dry. If you are short on time, skip the soak and focus on very thorough drying.

In a large bowl, toss wedges with lemon juice, salt, and oil until lightly coated.

Stir cornstarch and all dry spices in a small bowl. Sprinkle over the wedges and toss until the surfaces look evenly dusty and no dry pockets of starch remain. Let sit 5 minutes while you preheat the air fryer.

Preheat the air fryer to 200°C (390°F) if your model allows preheat.

Arrange wedges in a single layer with a little space between pieces. Air fry 18 to 24 minutes, flipping or shaking once halfway through, until the outsides are deeply golden and a knife slides into the center without resistance. Thicker wedges lean toward the longer range.

Work in a second batch if needed. Second batches often finish a minute faster because the machine is fully hot. Optional: for extra color on batch one, add 1 to 2 minutes at 210°C (410°F) at the end, watching closely so spices do not burn.

Transfer to a plate, sprinkle chaat masala if using, squeeze lemon, and scatter coriander. Serve hot.