Take a pan add heat the oil.

Add cumin seeds and roast it.

Add onion and tomato and saute it.

Add turmeric powder, salt, red chilli powder, dry coriander powder and mix well.

Add boiled and mashed potato and mix well and cook it for one minute.

Now take the idli and cut into the center.

Now take the one part of idli and spread the mixture on it and cover it with another part of idli.

Take a Tava and apply oil and roast it from both side.

Serve it with ketch up.