Put lentils and water on high heat and bring to the boil. Reduce heat and skim any scum off the surface. Add shallots, ginger, garlic, turmeric, salt and chillies and cook partially covered on a medium low heat for about 45 minutes or until dahl reaches desired consistency.
When lentils are ready, in a separate pan heat oil over high heat, add chillies and fry till brown. Then add seeds and cook till mustard seeds begin to pop.
Pour oil with chillies and seeds into dahl, throw in coriander and cover immediately to trap flavours. (If you like you can simply use coriander and not worry about the chillies and seeds)