Add chana dal, urad dal and whole dry red chilli and roast on a low flame until golden brown.
Now add chopped onion, garlic and saute well.
Now add tomato, saute until tomato becomes soft and mushy.
Take it out in a plate and let it cool down completely.
Once it gets cold put this mixture in a blender.
Add small piece of tamarind, salt and water.
Blend everything in a smooth paste.
Now in a small pan, heat 2 tsp oil.
Add mustard seeds to it and let it crackle.
Add urad dal and curry leaves.
Saute till the curry leaves become crisp.
Pour the tempering mixture in the kara chutney. Mix well.
Serve kara chutney along with idli, dosa, paniyaram or uttapam.
Notes
You can avoid adding tamarind if it is not available.You can add less chili if you don't want a spiced chutney or else you can remove the seeds of it before using it.You can add less or more water depending on the consistency of the chutney.