Add 1 tbsp of oil in a kadai and fry urad and bengal gram till golden.
Then add small onions,ginger and green chillies.
When onions are translucent add tomatoes with some salt.
Saute tomatoes till soft with all the rawness gone.
Add mint leaves.
After it shrinks switch off.
Cool the mixture and grind smooth by adding needed water.
Do tempering with mustard and curry leaves.
Serve with idli or dosa.
Notes
You can increase the amount of mint leaves if you want more green colour.
I have used country variety tomatoes for tanginess.
You can add little hing while doing tempering.
The best part of this chutney is that we don't need to add any coconut.