Spread the lentils out on a large flat plate. Run your fingers through the lentils to check for any damaged or shriveled bits, stones or other foreign matter. Discard any dirt or damaged lentils.

Place the lentils in a bowl under running water. Wash the lentils by swishing them around in the water with your hands and drain. Repeat this process about four times or until the water is clear. Drain and set the lentils aside.

Soak softer lentils such as split red and yellow in plain water. Fill a bowl with water. Place the washed lentils in the bowl. Cover the bowl and let the lentils soften for 30 minutes to one hour.

Use hot water to soak the harder variety of lentils such as green and brown. Fill a saucepan with water and heat until medium hot. Remove the water from the heat source. Place the washed lentils in the saucepan. Cover and let it soak overnight or for around 12 hours.

Discard the water in which the lentils were soaking. Set a pot on medium heat. Pour 1 tablespoon of oil and seasonings such as cumin, turmeric, salt and pepper, according to your preference. Add the lentils and water. Use 2 cups water for every 1 cup lentil. Allow green and brown lentils to simmer for 40 minutes to an hour. Cook split red, yellow and puy lentils for around 25 minutes.