Boil the potatoes , peel and cut into cubes.
Make a fine paste of onions.
Purée the tomatoes.
HeT oil in a pan.
Add cumin seeds, let crackle.
Add garlic paste , sauté on medium flame for two minutes .
Add onion paste , continue to sauté on medium flame . Sauté till there is no moisture . The onion will be still white.
Add turmeric powder and stir for a minute.
Add the tomato purée and let cook till oil separates.
Add red chilly powder, coriander powder , cumin powder .
Let the spices cook for a minute or two .
Add the cubes potatoes and salt .
Cook on medium flame , cover the potatoes for 4-5 minutes . Make sure you stir them in between .
Cover and keep aside for at least a couple of hours before serving . This will help in infusing the flavors .
Serve garnished with coriander.