Wash both the lentils thoroughly and soak them overnight.
Drain the water from the lentils and pressure cook them with 4 cups of water until the red kidney beans are cooked.
In a separate deep bottomed vessel, heat the oil and butter together. Add the cumin seeds to it and let them splutter.
Add the onion, ginger, garlic and the green chilli to it. Let the onions fry until brown.
Add the tomatoes and red chilli powder and fry until the tomatoes become soft.
Add the lentils to this and boil. Add some water if the mixture is too thick.
Add the garam masala to the gravy.
Garnish with cream and serve hot with rice or roti or naan.