Heat a pressure cooker and melt the butter. Add chopped garlic and saute for about 30 seconds.
Next add the onions and stir fry until they turn soft.
Add finely chopped tomato and saute until they turn mushy.
Now add soaked kidney beans and stir fry for a minute or so. Add 2 cups of drinking water.
Put on the lid and pressure cook for 2 -3 whistles and then simmer for 5-7 minutes.
Turn off the flame and let the steam escape naturally. Check if the beans are cooked well, by pressing the cooked beans between thumb and fingers. If it can’t be mashed easily, cook again till done.
Either with the back of a spoon or a hand blender, blend the bean mixture to get a soup consistency. It won’t be entirely smooth, but most of the cooked beans should be mashed. If required, add 1/2 cup of drinking water or more.
Turn on the flame and let the soup to boil again.
Season the soup with black pepper and lemon juice. You may add a little salt if you like; I skipped it.
Turn off the flame and serve the soup while warm.