To prepare sambar, clean, wash and soak dal in water for 15 – 20 minutes.
While dal is soaked clean and chop the vegetables for the sambar.
Transfer dal to pressure cooker with chopped vegetable, tomato, turmeric powder, red chili powder, salt and 2 Cups of water.
Cook dal in in the pressure cooker for 2 – 3 whistles on medium to high flame. The dal should become soft and mushy. Turn off the heat and release the steam from the pressure cooker.
Open the lid of pressure cooker and add chopped drumstick. Stir well and once again pressure cook dal on medium to high flame till 1 whistle comes. Turn off the heat and let the steam release from the cooker on its own.
Remove the lid of pressure cooker and add the sambar powder, tamarind paste, jaggery. Stir to combine well if the consistency of sambar is thick, then add more water.
Transfer sambar to a saucepan and then simmer the sambar for 10-12 minutes on a low flame stirring regularly in between so that the dal does not stick to the bottom.
Meanwhile prepare tempering, in a small pan, heat ghee over medium heat. Add mustard seeds once they crackle add onion, garlic, red chilies, asafoetida and curry leaves.
Fry till the garlic turns a light brown and the onion turn translucent. Pour the whole tempering in the steaming hot sambar. Close with a lid so that the flavors infuse for about 5-6 minutes.
Serve Sambar warm with idli, dosa or rice.