Combine potato with turmeric powder, red chilli powder, coriander powder, garam masala powder and chaat masala.Mix well and set aside to marinate.
Heat oil in a non-stick pan. Add cumin seeds and when they change colour, add onion and green chillies. Saute till onions are brown.
Add asafoetida, marinated potato and salt. Mix well and cook on medium heat for about fifteen minutes. Cook for a minute. Garnish with coriander leaves and serve hot with steamed rice and dal or rotis.