In a bowl wash the lentils well with a few changes of water or until the water runs clear. Soak the lentils in fresh water for atleast 2 hours.
In a kadai or cooker put 4 tbsp. of oil. When the oil gets hot add in the cumin seeds and green chillies. Fry for 2 minutes.
Add in the soaked lentils along with the water that it was soaking in. Add in the turmeric powder and salt; mix well.
Let it simmer on low heat - covered for about 12 minutes or until the lentils are well done