Finely chop tomatoes and onion store separately.make a paste of ginger and garlic.chop fresh coriander leaves.

Heat oil in heavy bottomed non stick pan.add onion and saute till translucent for about 2 mins.add salt,ginger- garlic paste, turmeric and cumin saute for a mint till the raw flavours leave

Low heat and cook till tomatoes are mashed up to a soft smooth paste about 10 minutes stirring continuously

Add the mushrooms cover and cook for 20 mint on low heat.