Add oil to a pot.
When oil is hot add asafetida and black cumin seed.
After a minute add garlic and fry for half a minute. Then add onion and fry till golden.
Add ginger and fry for a minute then add salt, chili, turmeric, cumin powders and mix.
Now add chopped tomato mix and cook on low medium heat till mushy and oil comes out.
Add boiled potato, stir and mix till potato is coated well with spices. Fry 2 to 3 minute then add 1-1/2 cup warm water. Mix then cover and cook for 8 minute on low medium heat.
Now add sugar and mix. Then add garam masala. Mix well then add cilantro, mix. Take off heat and serve.