Wash and soak kidney beans for 4-6 hours . Discard water and pressure cook soaked rajma/kidney beans with 3 cups of water and ½tsp of salt in a pressure cooker for 3-4 whistles or you can use canned red kidney beans If you are in a hurry.
Heat oil in a thick pan, cook onion and green chilli paste in oil till it is light brown in colour.
Add tomato puree and also turmeric powder, red chilli powder and little bit of salt if required.
Cook the masala paste over medium heat for 6-7 minutes till it starts to leave the sides of pan.
Immediately add cooked kidney beans along the liquid and mix it well with masala paste, add garam masala and cook for 10 minutes.
Serve it over a bed of steamed basmati rice/chawal for a perfect Rajma Chawal meal.