Boil, peel, and roughly crush potatoes into irregular chunks.
Heat vegetable oil in a pan, crackle mustard seeds and cumin seeds.
Add ginger paste, chopped green chili, and chopped tomatoes; sauté until soft.
Add turmeric powder, red chili powder, coriander powder, and salt; cook for 2 minutes.
Stir in crushed potatoes and water; bring to a vigorous boil and simmer for 10 minutes to form a flavorful fluid gravy.