Heat oil in a non-stick pan. Add asafoetida, coriander seeds, mustard seeds, dried red chillies, green chillies and ginger and sauté for a minute.
Add potatoes, mix well and sauté till the potatoes are lightly browned.
Add ¼ tsp red chilli powder, ¼ tsp roasted cumin powder and salt and mix well.
Add salt to the yogurt, mix and keep aside.
Transfer the potato mixture into a serving bowl. Add dried mango powder, 1½ cups yogurt and mix well. Spread the remaining yogurt on top.
Sprinkle red chilli powder and roasted cumin powder and serve chilled.