In a bowl, soak the potato slices in cold water for 10 minutes, then rinse under cold running water to remove any excess starch. Dry the potatoes on paper towels.
In a wide saucepan, heat the oil over a medium-high heat. Add the cumin seeds to the pan, followed by the dried red chillies. Cook, stirring, for a few seconds until the cumin seeds and chillies darken and release their aromas.
Add the potato slices to the pan in a single layer, trying not to overlap them, then add the salt. Allow the oil to return to a medium heat before lowering.
Gently cook over a low heat until the potatoes take on a translucent glaze and break easily. To prevent the potatoes from breaking up during cooking, do not stir too often – the best way to ensure even cooking is to shake the pan and then carefully turn the potatoes.