Take curd in a bowl. Add in the turmeric, coriander, chilli powders. Dilute with water and beat well to buttermilk consistency.
Chop potatoes and keep aside.
Now heat oil in a kadhai. Add cumin seeds, asafoetida and fenugreek seeds. Let them sputter. It takes about 30 seconds. Add in the ginger paste and curry leaves and fry for one minute.
Now add the chopped potatoes and slit green chillies and fry them for a couple of minutes.
Lower the flame and add the curd-spices mix gently.
Stir well. Add salt. Cook on medium flame till the curry comes to a boil. This takes about 3-4 minutes.
Now taste and adjust seasoning.
Garnish with chopped coriander leaves.
Your dahi ke aloo is ready to serve with rotis or boiled rice.
Easy, isn't it?