Heat coconut oil in a pot and add mustard seeds. When they start to splutter add onions and garlic. Fry for a couple of minutes. Add sweet potatoes, carrots and lentils and fry for a couple of minutes more. Add the hot water and let it come to a boil. Cover and let it simmer for 10 minutes. Add spices, ginger and coconut milk and let it come to a boil again. Blend either with a hand blender or use a regular blender. Serve!