Wash the mint and coriander leaves with water. Pick mint leaves discarding the stems. Chop coriander roughly discarding hard stems. Thin stems are okay to keep.
In a blender/food processor add mint, coriander, green chillies, salt and little bit of water. Grind until puree/paste is formed.
Serve it as a green sauce or add a table spoon to a cup of yoghurt to make raita.
Notes
If you are using it as green chutney you can add 2 cloves of garlic and a tablespoon of lemon juice.