Boil rice in the normal way.
Heat oil in a pan or a kadai.
Add mustard seeds, curry leaves, asafoetida, Bengal gram and black gram and red chillies.
Add groundnuts and fry for about a minute.
Put all the vegetables (except tomatoes and mashed potatoes) along with little water.
Cook it for 5-7 minutes till half done.
Add tomatoes and cook further for about a minute.
Add mashed potatoes, salt, turmeric powder, sambar powder, tamarind water and sugar.
Add boiled rice and mix well. Cover it with a lid and simmer for 5-7 minutes. The rice should not get too dry.
Sprinkle chopped coriander leaves.
:- Serve hot.