Wash the toor dal and pressure cook it with 2 cups of water until it becomes soft and mushy. Alternatively, you can cook the dal in a saucepan until soft.
In a skillet or kadhai, heat oil over medium heat. Add mustard seeds and let them splutter. Add cumin seeds and curry leaves and sauté for 1 minute.
Add chopped onions and sauté until they become translucent.
Add chopped tomatoes, carrots, potatoes, drumstick, and mixed vegetables to the skillet and mix well.
Add turmeric powder, sambar powder, and salt to taste. Mix everything well.
Add 2 cups of water and bring everything to a boil. Reduce the heat and let it simmer until the vegetables are cooked through.
Add the cooked toor dal to the skillet and mix well. Add more water if needed to adjust the consistency.
Add tamarind pulp and mix well. Let it simmer for 5-10 minutes.
Garnish with chopped coriander leaves and serve hot with steamed rice or idli.