1Place drumstick stems in a pot and add water to cover.
2Boil the drumstick stems until cooked.
3Strain the liquid into a separate container and set aside the stems.
4In a blender, combine cumin seeds, black peppercorns, turmeric powder, garlic cloves, chopped tomatoes, and a handful of fresh coriander leaves, then blend.
5Pour the water used for boiling the stems into the blended mixture and stir.
6Heat oil in a pan, add mustard seeds, dry red chilies, and curry leaves to temper.
7Add sliced green chili and pour in the blended rasam mixture.
8Bring the rasam to a simmer, then add the reserved boiled drumstick stems.