Put the lentils into a sacuepan and add the 3 2/3 cups water. Bring it to a boil and simmer for 20 minutes or until tender.
Using a mortar and pestle(or food processor), crush the fresh ginger, 2/3 of the chilies, and 2 of the garlic cloves until smooth. Add to the lentils.
Add the coconut milk, turmeric, ground ginger, lemon juice, and salt to taste. Cook gently, stirring for 1 minute, then increase the heat and cook for 5 minutes, or until any excess liquid has evaporated. Taste for seasoning.
Crush the remaining garlic and set aside. Melt the butter in a skillet and add the mustard seeds. As soon as they begin to pop, remove the skillet from the heat and stir in the crushed garlic and the remaining chopped chili.
Transfer the lentil mixture to a warm serving dish and top with the garlic,chili, and mustard seed butter. Serve immediately. Enjoy!