Soak the tamarind in warm water for 10 minutes.Squeeze it and take out the extract adding extra water. Alternatively, you can heat it in the microwave for 1 minute or use 1 tbsp of tamarind paste too.
Cut the drumstick into 3" pieces
Heat oil in a kadai. Add mustard seeds, fenugreek seeds, tuvar dal and asafoetida and saute till the mustard starts to crackle
When the mustard crackles add the cut drumstick pieces and saute for few seconds
Next, add the curry leaves too and saute for few seconds.
Now add the vatha kuzhambu podi and let it fry in the oil for a minute. This brings out the good flavour for the kuzhambu.
Now the burner on the high mode and add the tamarind extract plus another cup of water. Add salt. Cover with a glass lid at this point and let it boil. Covering helps the drumstick to cook faster
After 3-4 minutes, it tends to become thicker. Now take out the lid, and lower the flame.
Add the jaggery and mix well and continue to cook on low flame for another minute. Do not skip adding the jaggery because it adds to the unique taste of vathal kuzhambu
Now take gram flour, add little water and make it into a diluted paste and add this to the kuzhambu. Mix well and let the kuzhambu boil for another 2 minutes. Adding gram flour thickens the kuzhambu
Now the kuzhambu has thickened to the required consistency. Switch off the fire and serve hot with rice and a curry