Take 2 glasses of water in a vessel and put tomatoes in it.
Boil the tomatoes for 5 - 7 mins.
Take the tomatoes out and let them cool.
Remove the skin from the tomatoes and mash them.
Heat oil in a pan.
Splutter mustard seeds.
Add curry leaves, black gram, half red chilly and asafoetida.
Add mashed tomatoes, tamarind juice and salt. Stir it for 2 mins.
Remove from the stove.
:- Serve with idli, dosa or anything else you fancy.