Wash and cut the potatoes in half and pressure cook for 3-5 whistles or until cooked. Set aside to cool.
Peal the skin of the potatoes and mash them in a bowl. Keep aside.
Take a pan, on medium heat, add oil, black gram and mustard seeds.
Once the mustard seeds start to sputter, add finely chopped onions, curry leaves and green chilli. Fry till golden brown.
Add the mashed potatoes to the onions. Fry for 10 min.
Add turmeric, red chilli powder and salt. Mix well and fry for 5 min.
Serve hot with rice or roti.