Cook the Toor Dal: Rinse the toor dal and cook it in a pressure cooker with water for 3-4 whistles, until soft and mushy. Mash the dal with a spoon.
Prepare the Tamarind Pulp: Soak tamarind in warm water for 15 minutes and extract the pulp, straining to remove any solids.
Cook the Vegetables: In a separate pot, cook the vegetables (carrots, potatoes, drumsticks, etc.) in water until tender.
Prepare the Sambar Base: In a large pot, combine the cooked dal, tamarind pulp, vegetables, sambar powder, and turmeric powder. Add water to adjust the consistency.
Simmer the Sambar: Allow the sambar to simmer on medium heat for 10-15 minutes, allowing the flavors to combine.
Tempering: Heat oil in a small pan, add mustard seeds, curry leaves, dried red chilies, and asafoetida. Once the mustard seeds splutter, pour the tempering into the simmering sambar. Stir well.