Cook mushrooms with salt (without adding water) and keep it aside.
Meanwhile in a wok, pour olive oil and add cumin seeds.
Then, add ginger, garlic, green chillies and onion pieces.
Cook for 4 minutes.
Add tomatoes followed by all the powders and saute till the raw smell goes.
Put half of this masala along with cashew nuts and water in a grinder and make it into a gravy.
Pour this gravy into the wok and add cooked mushrooms. Allow it to boil for 2 minutes.
Finally, add garam masala.
:- Serve hot with chapathis.