Soak tamarind in one cup of water and strain.
Heat oil in a non stick kadai add mustard seed and methi seeds. When it starts spluttering add ginger, green chillies, curry leaves and red chillies saute till fragrant.
Add red chilli powder and mix in the tamarind pulp and keep stirring and cooking till turns thick. Add jaggery, red chilli powder and salt and saute for a minute.Remove from heat and cool. Store in a jar.
Serve hot with kerala dishes and with Thayir Sadam (Curd Rice).