Cut green chillies into 1 inch pieces
Peel potatoes and cut into 1 inch or smaller cubes
Crush the peanuts coarsely
Heat oil in a pan. Put in the mustard seeds. When they begin to pop, fry the green chillies and potatoes in the oil until they just begin to change colour
Add the crushed peanuts, tamarind juice, sugar and salt
Add a little water and cook very slowly until the potatoes are cooked
Meanwhile, pound the boiled gram daal in a bowl and add the sesame seeds and coconut and pound a little longer
Add the chilli powder
Mix this with the green chillies and potatoes
Stir well and simmer for 5 minutes
Serve hot with puns, rotlis or parathas