Heat oil in a pressure cooker. Slice onion and add along with curry leaves. Slit green chillies and add with sambhar onions and sauté.
Cut potatoes into small cubes.
Add turmeric powder, asafoetida and red chilli powder and mix. Add potatoes and mix. Add rice and toor dal and mix well. Add 5 cups water and let it come to a boil.
Meanwhile for the masala dry roast chana dal, urad dal, green cardamoms, cloves, fenugreek seeds, cumin seeds, cinnamon and dried red chillies in a non stick pan till fragrant. Cool and grind to a powder.
Chop tomatoes and add to the cooker. Add green peas and mix. You can also drumsticks if you wish.
Add sambhar masala and mix. Close the cooker with the lid and cook under pressure till 3 whistles are given out.
Open the lid when the pressure reduces completely.
Heat ghee in a shallow non stick pan. Add 4 tsps of the powdered masala and tamarind pulp to the cooker and mix well. Add salt and mix and simmer on medium heat.
When ghee in the pan melts, add mustard seeds, red chillies and curry leaves and add to the cooker and mix well.
Serve hot with potato chips.