Heat the oil in the kadai and add mustard seeds and urad dhal.
As urad dhal turns light brown, keep aside a small amount of this tempering/tadka to add later to the thuvaiyal.
To the remaining, add the red chillies, green chilly and shallots.
Saute it till the raw smell goes from the shallots and they become tender.
Let it cool.
Grind together with cilantro and salt. Don’t need to add water.
Now add the tempering/tadka and mix well.
If you grind this chutney without adding water, it can stay for upto 1 week. You can sauté the cilantro also along with shallots, if you want to avoid the raw smell. Adjust the salt and spices according to your preference.