If you are pre-cooking the lentils prior to adding them to your dish, here's how to do it. Rinse and drain 1 cup of lentils. Bring 4 cups of water or vegetable broth to a boil. Add rinsed and drained lentils. Bring back to a boil. Reduce the heat and cover. Simmer for 5-8 minutes. Remove from the heat. Drain excess water. Stir in your curry or another dish. Cooking time will vary depending on the type of lentils you use. This cooking time is for red or yellow lentils. Green or brown lentils will require a longer cooking time.