Wash dal several times in running water.
Soak the dal for at least 10 minutes.
In a pressure cooker add soaked toor dal, 2 cups water, garlic cloves and castor oil.
Pressure cook on high flame for 3 whistles and simmer for 10 mins. Let the pressure release naturally.
Meanwhile in a pan heat oil, add mustard seeds. Once the mustard seeds crackle, add chana dal, urad dal and cumin seeds. Add asafoetida.
Once the dals are roasted, add chopped shallots, red chillies, green chillies and curry leaves.
Once the shallots turn translucent, add chopped tomatoes.
Saute till the tomatoes turn mushy.
Now add sambar powder, turmeric powder, mix well and switch off the flame.
In the same pressure cooker, mash the dal slightly, add the chopped vegetables and 1 ½ cups of water and bring it to a boil. You can adjust the quantity of water as per your need. This yields a thick sambar. If you need a slightly runny one add half a cup of extra water.
Now add the tempered mixture and mix well.
Add tamarind water or tamarind paste.
Add required salt.
Pressure cook on high flame for just 1 whistle and release the pressure manually since we have used drumsticks. If you are not using drumsticks you can allow the pressure to release naturally.
Garnish with coriander leaves.
Serve hot !!!