Add salt and two plum tomatoes and fry for further 5 mins,
Add Curry powder, curry leaf and mix
When paste begins to form add rest of can of plum tomatoes.
Add potatoes, stir and cover with water.
Cover and simmer.
When potatoes are half cooked add 3 cans of butter beans and chopped coriander.
Simmer for further ten mins until potatoes are soft.
Sprinkle with garam masala
Serve with rice.