Heat a pan with oil. Add mustard seeds and when they splutter, add asafetida, curry leaf, onion, slit green chilies, tomatoes and cook for 2-3 minutes or till the tomatoes turn mushy.
Add cooked carrots and mix well.
Add tamarind pulp, red chili powder, 1/2 cup water, salt and cook for 5 minutes over low flame till the raw smell disappears.
Add the mashed dal, mix well. Add more water if needed to adjust the consistency.
Sprinkle the ground spice powder and mix well. You can also mix the powder with water in a small bowl and add it to the sambar to avoid lumps.
Let the sambar cook for 2-3 minutes till all the flavors merge together.
Tiffin sambar is ready.
Garnish with coriander leaves.
Serve piping hot with idlis, dosas, medhu vada and pongal.