Mix black lentils and red kidney beans and soak them in 4 cups water overnight.
Next day, remove the water, wash the lentils and put them to boil in a big pot with 5 cups of water.
Once it starts to boil, reduce the heat to medium and let it cook for 1 hour. (Keep removing foam from the top).
Add ginger-garlic paste, tomato puree, red chili powder, butter, salt and 1 cup of water cook for half an hour on medium heat.
Add full cream and cook for another half an hour on high - medium heat or until the lentils have become softer (You might need to add another cup of water if the consistency of lentils is too thick at this step).
Transfer to a serving bowl; garnish with butter, onion rings and green chili and serve with rice/naan/bread.
Cooking time of lentils depends on the type of pot and heat you use.