Roughly chop mint, coriander and mint. Add to a blender with lemon juice, ground cumin, chilis, and salt to taste. Blend until smooth, adding a little dribble of water if you're having a difficult time blending.
Transfer blended herb mixture to a bowl with yogurt. Mix until well combined.
Serve alongside roast chicken/veggies, and as a dip for toasted pita/naan.