Heat oil in a kadai or a heavy bottomed pot.
Add ajwain seeds. When the seeds splutter add asafetida and green chilies.
Saute for few seconds.
Add the tomato puree, salt and curry leaves.
Sauté & cook covered for 10 min or low heat.
Add red chili powder and turmeric powder.
Cook covered on low heat till oil separates.
Add the potatoes and sauté for 5 minutes.
Add sufficient water to make gravy.
Boil on a medium flame till the gravy thickens.
Add grated ginger and garam masala powder & Mix.
Garnish with coriander leaves.
Serve hot with garam roti, crisp paratha or purees.