Rinse, dry and sort lentils, removing any stones. Cover lentils with 2 inches of water in a pot and bring to a boil. Lower heat, place lid on pot, and simmer 30 to 40 minutes or until lentils are very tender. Strain well.
Pour oil in frying pan and cook onion, turmeric, cumin seeds, and red pepper 5 to 8 minutes or until soft. Set aside 1/4 cup onion mixture.
Add lentils to frying pan and cook, stirring almost constantly, over low heat 10 to 20 minutes or until mixture is thick. Mix in cilantro and salt.
When ready to serve, top with saved onion mixture and lemon rinds.