Heat mustard oil in a pan. Add onions and sauté till they are golden brown - about 4 to 5 minutes. Add green chillies and sauté and then add chilli powder, haldi, amchur, salt and potato. Sauté for 30 seconds and turn off the flame. Let this cool for 2 minutes and add the whisked curd and mix. Top with coriander and serve.
2 tbsp Mustard Oil, 1 large onion, 1-2 green chillies, 1 tsp Kashmiri Chilli Powder, 1/2 tsp Haldi, 1/2 tsp Amchur, 1/2 tsp Salt, 1 boiled Potato, 2 cups whisked Dahi, 1-2 tablespoon Chopped coriander