In a pan, heat 2 tbsp oil and add ¼ tsp mustard seeds, a pinch of hing, 1 tsp chana dal, 4-5 methi seeds, 2 dry red chilies, and some curry leaves. Sauté them.
Add 1 small sliced onion and sauté it. Then add 1 chopped green chili and 1 tsp ginger-garlic paste. Sauté well.
In a bowl, mix ½ tsp turmeric powder, 1 tsp Kashmiri red chili powder, 1 tbsp coriander powder, 1 tbsp sambar masala, and some water to make a masala paste.
Add the masala paste to the tempering and sauté until the oil releases from the sides.
Add 2 cups of hot water and salt. Mix well and bring it to a boil.
Add 1 chopped tomato, ½ cup dudhi pieces, and 1 chopped drumstick. Also, add 1 tbsp tamarind pulp and 1 tbsp jaggery. Mix well and let it boil for 8-9 minutes on low flame until the vegetables are properly cooked.
Add 1 cup of leftover dal, mix well, and boil the sambar for 5-7 minutes.
Garnish with coriander leaves. The sambar is ready to be served with medu vada.