Boil in water and cook the potato by cutting them into 1½ inch cube.
Grind coriander seeds, dry chili, cumin seeds into a fine paste by adding little water as possible. Now add salt, coconut, ¼ cup of water and grind it to a paste. Now add shallot, garlic and grind to a thick paste.
In a pan heat oil, now add mustard seeds once the mustard seeds stop splattering add chopped onion, curry leaves and cook until onion become translucent (golden brown).
Now add cooked potato and sauté for 2 minutes. Now add turmeric powder and sauté for a minute.
Now add the ground paste and sauté until the oil separates (takes about 5 minutes) and serve.