1. Heat sufficient water in a deep non-stick pan and blanch the purple yam. Drain.
2. Heat oil in another non-stick pan, add the purple yam and sauté for two minutes on medium heat.
3. Add the black salt, salt, red chilli powder, chaat masala, mix well and cook on a medium heat for eight to ten minutes or till the purple yam turns to golden brown in colour.
4. Serve immediately.