Soak rajma, urad daal and chana dal overnight.
Pressure cook the urad dal, chana dal and rajma. Mash them a little. Keep aside.
Heat butter in a pan, add mustard seeds and cumin seeds and fry until they splutter. Add ginger and chillies.
Fry for few minutes. Add chopped onions and tomatoes. Cook until done.
Add salt, red chilli powder, turmeric powder and stir well.
Add the mashed dals and boil for few minutes.
Add cream, corainder leaves and mix well. Serve the dal maharani hot with roti.