Soak the tamarind in warm water. Extract the juice and discard pulp and seeds
Heat oil and add the black mustard seeds. When they pop, add the urad dal
When the dal turns golden brown, add the cashew nuts or peanuts
Roast until golden brown
Then add the onions, curry leaves, red chillies, and hing
Mix well and saute until the onions turn translucent
Now add the tamarind water
Also add the brown sugar and jaggery at this time
Cook on low flame until the mixture thickens, about 4-5 mins
Then add the idiyappam and salt
Mix well and cook for another minute until the moisture is absorbed almost entirely
Serve hot as is or with red coconut chutney