This is the Palakkad Brahmin way of making sambar.
Saute vegetables for a minute to remove the raw smell.
Pressure cook dal till its cooked soft.
Soak tamarind in hot water and extract its juice.
Boil the vegetables in water alongwith salt, turmeric and tamarind juice.
Dry roast fenugreek seeds, coriander seeds, red chillies, asafoetida and grated coconut. If coriander seeds are not available, you can use coriander powder too.
Grind the above roasted mixture into a smooth paste.
Mash the pressure cooked dal.
Add the dal to the boiled vegetables.
Add the ground mixture to the above mixture and heat well.
Crackle mustard seeds in a little oil.
Add the mustard seeds and curry leaves to the sambar.