Prepare Tamarind: If using a tamarind ball, soak it in warm water for 10-15 minutes. Extract the pulp by squeezing and straining it.
Cook Lentils: In a large pot, add lentils with 2 cups of water. Bring it to a boil and cook until the lentils are soft. You can also use a pressure cooker for faster cooking.
Make the Saaru Base: In a small pan, heat oil and add mustard seeds, cumin seeds, black pepper, dried red chilies, and curry leaves. Once the mustard seeds splutter, add the chopped tomato and cook until softened.
Combine the Mixture: Add the tamarind pulp, turmeric powder, green chilies, and jaggery (if using) to the lentils in the large pot. Stir to combine and let it simmer for about 10 minutes, allowing the flavors to meld.
Adjust Consistency: If the saaru is too thick, add a little water to reach your desired consistency. Taste and adjust salt and jaggery if needed.
Serve: Garnish with fresh coriander leaves and serve hot with steamed rice or as a side to other South Indian dishes.
