Heat oil in a kadhai, add mustard seeds and jeera.

Add onion and green chillies and mix.cook for 2 minutes.

Add tomatoes and mix. Cook for 2 minutes.

Add salt, coriander powder, Red chilli powder and turmeric powder and mix.

When masala is done, add mashed potatoes and mix and cook for 2 minutes.

Add 1 glass of water and let it cook for 10 minutes.

Add coriander leaves and garam masala. Switch off the flame.

Serve with plain rice or chapati.