Add the coconut, roasted gram, green chilli, onion and salt in a blender. Grind them to a fine paste. Add water in between grinding based on how thick you need your chutney.
Once the chutney is ready. Heat a kadai in low flame. Add oil to it. Once the oil heats add mustard to it. Once it splutters add curry leaves and dry chilli to it and roast it and switch off the stove and garnish the chutney.
Now the chutney is ready. Serve it as sidedish with Idli, Dosa, Pongal, Chapati, Baji or Bonda.