Heat oil in a kadai add grated coconut,red chili,coriander seeds,cumin seeds,saumb,cardamom,cinnamon and cloves.Saute for 2 minutes.
Add chili powder and turmeric powder saute for 2 minutes until coconut becomes golden brown
Add cashew nuts and salt to this .then switch of gas stove.
Grind all this spices in a mixer.
Heat oil in another kadai add mustard when it splutters add red chili and onions,saute for a minute.
Add curry leaves to this and saute for a minute.
Add cleaned mushrooms and grinded masala to this .
Add tomatoes,salt and water to this and boil for 10 minutes,until it is cooked well.
Now chettinadu mushroom curry is ready to serve.It goes well withl rice and chapati.