Bring a saucepan of water to the boil, and have a bowl of iced water on standby.
Shock the mint and coriander leaves in the boiling water for 3–5 seconds, then remove with tongs and plunge straight into the iced water. When cooled, dry the leaves on paper towel. (Blanching the leaves helps keep the chutney green and makes it easier to blend.)
Put the coriander and mint leaves in