1. Place toor dal, turmeric, salt, asoefetida and water in a saucepan; bring to a boil, then reduce heat and simmer until dal is cooked, adding water if it evaporates, for about 30-45 minutes.
2. Place tempering ingredients in a small saute pan and heat until curry leaves begin to sputter, then add to dal soup.
3. Mix tamarind paste with hot water and the strain through a sieve, pressing with the back of a spoon to get all the pulp.
4. Place ingredients for sambar in the pan with the soup and top up with water to cover. Bring to a boil and then reduce heat and simmer for 30 minutes, or until vegetables are tender, adjusting water amount to your liking. If drumsticks are woody, discard them before serving.