Wash the red lentils under running water until the wash water runs clear. Then bring to the boil in 1 liter of water over medium heat and simmer with the saucepan open (caution - boil over quickly!) On a low flame until the lentils are soft and soupy. Set the lentils aside.
Heat the fat in a large saucepan or wok and fry the finely chopped onion and cumin until golden brown. Add the ginger and desiccated coconut and continue frying for about a minute - be careful, the desiccated coconut burns easily! Add the tomatoes, simmer on a low heat for about 5 minutes with the lid closed. Add the turmeric, chilli, salt, cream and lentils together with the cooking liquid and let everything simmer on a low flame for about 10-15 minutes.
Just before serving, season with coriander and garam masala (available in Asian shops as a powder or paste).