Heat oil in a pan / kadai , add cumin seeds when it splutters add chopped green chilies.
Now add ginger and garlic paste and saute till , raw smell goes off.
Add 1 sprig curry leaves and sliced onions, turmeric powder and saute till onions turns light golden color.
Add in chopped tomatoes and saute for 3-4 minutes , till tomatoes turns soft.
Add red chilli powder , coriander powder , garam masala and jeera powder , mix well everything.
Whilst wash mushroom , slice and add to the above mixture.
Gently saute for 2-3 minutes , add salt and sugar .
Mix well everything , cover with a lid and cook on medium heat for 5-6 minutes.
Open the lid , keep on low heat , add curds and mix well everything.
Allow it to blend well with spices and cook on low heat for 2-3 minutes.
Add ¼ cup of water , mix well and continue to cook further till specks of oil is seen on top.
Whilst , heat 1 tablespoon ghee / clarified butter in a seasoning pan.
Add cashews and curry leaves, allow cashews to turn light golden and curry leaves turn crisp.
Turn off the heat and add black pepper powder and mix well.
Pour temper over mushroom masala.
Add chopped coriander leaves , mix well everything and turn off the stove.
Serve mushroom masala with onion rings, lemon wedges alongside roti / phulka.