Fresh Curds or Yogurt: 2 cups
Potato: 2 medium size
Onion: 1 medium size
Coriander Leaves : Small bunch 
Oil : 1 tsp 
Mustard seeds : 1/2 tsp 
2 Green Chillies
Salt as per taste
Curry leaves: 8 to 10 leaves

Direction 

Cook potatoes and allow it to cool down. Now peel the skin of the baked potatoes. Grate them into small pieces. Chop coriander leaves, green chillies and onion. Take oil in a pan and add mustard seeds in it. Allow it to splutter. Add curry leaves and green chillies. Stir well. Keep it aside. Allow it to cool down. Now add chopped onion. Mix well, add oil containing mustard seeds, curry leaves and green chillies. Mix them. (while mixing potatoes might get mashed, so, do not mix very hard, if it gets mashed little bit it is OK). Now add curds and salt to it. Mix them. Garnish with coriander leaves. Serve with Chapatis or Biryani. 

*** For Details about Ingredients , check your nearest Indian Store