Wash and soak the split udad dal and rajma in plenty of water for minimum 6 hours or overnight.
Drain the soaked dals and place in a pressure cooker with 4-5 cups of water.
Close the pressure cooker lid and after 3 whistles, keep on sim (lowest flame) for 10-15 minutes. After this, turn off the flame and allow the cooker to cool.
Meanwhile, heat the oil+ghee in a heavy bottomed kadai.
Add the cumin seeds. Once they splutter, add ginger, garlic, asafoetida and onions. On a medium flame, cook this until onions are lightly golden and soft.
Add the pureed tomatoes, turmeric, red chilli powder, salt and bring to a simmer.
Simmer for 5-6 minutes, add the cooked dals from the pressure cooker, salt and bring to a simmer.
Allow this to simmer gently for another 5 minutes, after which you can sprinkle the garam masala powder, stir well and then remove from heat.
Garnish with lots of finely chopped coriander.
Serve hot with tandoori rotis or steamed rice.