Soak all lentils in water overnight. Wash four times, changing the water each time.
Boil all of the lentils with the ginger, garlic, chillies and salt in enough water to submerge all ingredients, adding water as required.
Simmer for 50 mins or until lentils are well cooked.
Mash the lentils lightly with the back of a ladle.
To make the tadka, heat the ghee until hot, and add the cumin seeds and fenugreek seeds, and stir until they crackle.
Add the garlic and fry until beginning to colour.
Add the asafoetida powder and tomato paste and stir for a minute.
Add tadka to the cooked dal, mixing well.
Bring the dal to the boil again, adding the chilli powder, butter and cream.
Simmer gently for 30 minutes.
Add the garam masala and lemon and adjust seasonings. YUM.