Soak tamarind in 1/2 cup or 1 cup of water and make thick juice.
Pressure cook pigeon pea until it become mashed (4 to 5 whistle) by adding water as needed (1 cup to 1 1/2 cup).
Dry or oil roast and grind all the ingredients under the section "-- Roast and to grind --" into a paste or power based on your choice.
Sauté chopped vegetables (brinjal, carrot, capsicum, potato) in oil. Once the vegetables is sautéed now add the tamarind juice, salt, sambar powder, water if needed and bring to boil. Boil for 3 to 4 minutes.
Now add the cooked pigeon pea and boil for 2 more minutes.
Now add the ground powder or paste and cook until raw smell is gone and right sambar consistency is reached and serve. NOTE: if you want to thicken it add some rice flour mixed in water and boil for 2 minutes.
Add shallot (sambar onion) or other vegetables as you like.