Wash the moong dal well and soak it in water for 15 minutes. Drain and transfer it to a pressure cooker.
Add chopped yellow pumpkin, onion, tomato, garlic cloves, tamarind, turmeric powder, sambar powder, salt, and water to the cooker.
Close the lid and pressure cook for 2 whistles. Allow the pressure to release naturally.
Open the cooker and gently mash the cooked pumpkin and dal using a ladle. Adjust the consistency by adding water if needed.
Heat oil in a small pan. Add mustard seeds and allow them to splutter.
Add asafoetida and dried red chillies. Saute for a few seconds until aromatic.
Pour the tempering over the sambar and mix well.
Simmer for 2 to 3 minutes and switch off the flame.
Serve hot with rice, idli, dosa, pongal, or chapathi.