Wash the potatoes and roughly chop them into 4 pieces. Pressure cook potatoes with salt and 2 cups water for 5 whistles in medium flame. Let the pressure release naturally. Peel the skin, mash the potatoes and keep aside
In a pan heat oil and add mustard seeds. Once mustard seeds crackle add urad dal, chana dal and cumin seeds.
Add finely chopped onions, green chillies, curry leaves, salt and turmeric powder and saute till onions turn translucent.
Add capsicum and saute for a minute.
Then add tomatoes and cook till mushy.
Now add mashed potatoes, mix well and add 1 ½ cups of water and bring it to boil. Check for hotness and salt. If you prefer you can add chilli powder at this stage to increase the hotness as per your preference.
Simmer for 5 minutes, garnish with coriander leaves and serve hot !!