To begin with : Heat oil in a kadai - add mustard seeds let it splutter first. Then add jeera let it crackle then add curry leaves, let it splutter.
After that add onion. Saute until transparent.
Next add ginger garlic paste and required salt.
Saute for 2 mins.
Now add tomatoes.
Saute until mushy. Mash with laddle and cook.
Cook covered for 2 mins or until raw smell leaves.
Add red chilli powder and coriander powder. Onion tomato thokku is gettng ready.
Saute for a minute or so. Do not burn the masalas.
Add 1/4 cup water.This is to avoid burning of masalas.This step is close to finish of onion tomato thokku.
Cook for 2 mins till it becomes a thokku consistency.
Switch off when oil floats at edges or on top.
Serve with chapathi, idli, dosa etc.