Soak tamarind in 1/2 cup hot water for 15 minutes. Now drain the water in a separate bowl by removing the pulp.
Pressure cook lentil with 1 cup water and a pinch of turmeric powder till its soft and cooked properly. Mash the lentil and keep it aside.
Add 1 tbsp oil in a sauce pan and when its warm, add drumsticks and saute for a minute.
Lower the flame and add tamarind water, turmeric powder, sambar powder, jaggery and let it simmer for few more minutes.
Add mashed lentil, salt to taste and mix it well. If you feel its took thick, you can add some more water and adjust the consistency.
Add 1 tbsp oil in a small frying pan and when its warm add mustard seeds. When mustard seeds splutter, add red chillies
Add a pinch of asafoetida, curry leaves and stir for few second. Add this tempering in the Sambar and serve it hot with some rice or Idli/Dosa.