Heat oil in a pan. Add urad dal and whole dry red chilies and saute over low flame till they are roasted to golden brown.
Drain into a bowl and set aside.
Add garlic and ginger to the same pan and saute till they shrink in size and change color slightly.
Drain into the same bowl and let it cool.
Add mint, coriander leaves and curry leaves and saute till they shrink in size.
Take the pan off the stove and let it cool.
In a mixie jar, add the roasted dal, chilies, sauteed ginger - garlic, and the leaves.
Add soaked tamarind, salt and grind to a smooth paste using the same water used to soak tamarind.
Add more water if needed and check salt.
Heat oil in a pan for tempering.
Add mustard and when it splutters, add the ground chutney and mix.
Add little water to the mixie jar, rinse well and add to the pan.
Cook over low flame for 1 minute till it is smooth and take off fire.
Kadamba chutney is ready to be served with hot idlis and dosas.
It keeps well for upto 10 days when refrigerated.