Pressure cook rinsed toor dal with 3 cups of water, turmeric, and 1 tsp oil until mushy. Mash thoroughly until completely smooth.
Squeeze the soaked tamarind to extract all juice. Strain out and discard the seeds and pulp.
Cook the drumstick, carrots, pumpkin, shallots, and tomato in the tamarind liquid and salt until tender.
Stir sambar powder and the mashed dal into the simmering vegetable mixture. Simmer gently on low heat for 5-7 minutes.
Heat ghee in a pan. Splutter mustard seeds, then add curry leaves, dried red chilies, and hing. Fry for 30 seconds.
Pour the sizzling tempering into the sambar. Cover instantly to trap the aromas. Garnish with fresh cilantro.