Wash the lentils in warm water until the water runs clear. Soak in warm water for approximately an hour then drain.
Using a heavy bottomed saucepan, add the drained lentils along with 800ml of water. Bring to the boil and remove any scum that forms.
Now add the turmeric and the asafoetida. Cover and simmer until the lentils are almost cooked then add some salt. Allow the lentils to cook completely.
Using a separate wide frying pan, heat the ghee until hot, then add the asafoetida and the cumin seeds. Once they begin to splutter, which will take a couple of seconds, add the onions. Fry until the onions start to brown at the edges.
Now add the garlic, chillies and the ginger. Continue to fry, until the whole mixture turns golden brown.
Toss the onion mixture onto the lentils along with the garam masala.
Stir in the lime juice and the chopped coriander.
Serve in bowls with a small dollop of yoghurt drizzled over the chilli butter.