Wash the carrots, peel the skin and cut it into medium size pieces. Cut tomato into big pieces. Put both carrot and tomato pieces into a mixie jar and grind it to a fine puree by adding little water. Strain it and keep the puree aside.
Soak tamarind in water and squeeze out the juice.
In a dry kadai add thuvar dal, black pepper, cumin, fenugreek, red chillies, coriander seeds and dry fry till the dal turn golden colour. Cool it and powder it coarsely.
Pour the tamarind extract in a thick bottomed vessel. Add turmeric powder, asafoetida powder and salt. Bring to boil. When it starts boiling add the carrot puree and allow to boil.
When it starts boiling add coarsely ground powder and curry leaves. Allow to boil for few seconds. Season it with mustard. Finally add coriander leaves and remove.