Wash mussels well. Remove beards, any that are open when tapped, any broken ones and any that float. Blend garlic and ginger. Add 120ml of water and blend until smooth. Heat oil in a large pan. When hot add onion and fry until translucent. Now add the paste from the blender with chillies, tumeric, and cumin and fry for 1 minute. Add coconut, salt and remainder of water. Bring to boil. Add the mussels, mix well. Bring to boil. Cover and lower heat. Let mussels steam for 6 to 10 minutes or until they open. Discard any that don't open. Serve immediately.