Mix the two dals, wash and soak in four cups of water for an hour. Drain.
Place soaked dals in a pan with four cups of water, salt to taste, turmeric powder, half of the ginger and green chillies.
Cover and cook on low heat till the dals are tender. Stir well with a ladle to make a homogeneous mixture of the dals without mashing them.
Heat ghee and butter in a pan. Add cumin seeds, remaining green chillies and ginger.
Stir and add onion and sauté till onion turns light brown. A
Add tomatoes and sauté till the tomatoes soften. Add red chilli powder and sauté for half a minute. Add the tempering to the dal and mix.
Simmer for a few minutes and serve hot garnished with coriander leaves.