Clean the kulthi as it may have stones. Wash and soak it alongwith rajma in drinking water overnight or for 7-8 hours.
Next morning, put the soaked kulthi and rajma in pressure cooker alongwith water in which they were soaked.
Also add asafoetida, turmeric powder and salt.
Put a lid and pressure cook for 6-7 whistles.
In the meantime, add onion, tomatoes, green chilies, garlic and ginger in a blender jar.
Make a smooth puree.
Take oil in a pan and when it is hot, add cumin seeds.
When seeds begin to splutter, add the onion tomato paste in it. Also add red chili powder, coriander powder and garam masala. Cook the paste until oil separates.
By now the daal must have been cooked & pressure released. Add dal to the pan and mix.
Also add dry mango powder.
Let dal simmer for 1-2 minutes.
Serve after garnishing with coriander leaves.