Heat oil in a large kadhai or wok. Add mustard seeds, ginger, garlic, curry leaves, dried red chillies and stir fry for two minutes till you can start smelling all the aromatics.
Add tomato paste, coriander powder, cumin powder, chilli powder and garam masala.
Do not cut the mushrooms well in advance as they will start to lose moisture. Cut and use immediately.
Add the mushrooms, pepper and salt and cook on high heat.
Toss them regularly for a few minutes till the mushrooms leave water and reduce slightly in size.
Cooking on high heat prevents them from becoming soggy. Once the mushrooms are cooked, turn off the heat and serve.