Cut larger mushrooms into quarters and smaller ones into halves.

Heat oil and butter together in a large pan over medium heat.

Sauté the red onion until dark brown.

Add the grated ginger, grated garlic, ground cumin, ground coriander, ground turmeric, and cayenne to the pan.

Stir constantly over medium heat until the mixture turns golden brown, being careful not to burn it.

Add the chopped tomatoes and cilantro and sauté for another minute.

Add the peas and mushrooms to the spice mixture and mix well.

Add water and salt, and bring to a boil.

Reduce the heat to simmer, cover the pan, and cook until the mushrooms are tender, about 10 minutes.

Serve hot.