Heat oil, stir in chopped ginger, then garlic, then onions, and salt. Fry until onions are golden.
Add cumin, turmeric, ref chili.
Add tomatoes and most of the cilantro. Cook briskly until mixture draws away from the pan.
Add peas and potatoes, stir until covered.
Add 1 cup water, bring to boil. Lower heat and simmer 10 minutes (or until potatoes are done).