Heat oil in a saucepan. Add the mustard and cumin seeds and let them sputter.
Add the cloves, cinnamon, cardamom and bay leaves and stir for a minute. Add the onions, curry leaves, and green chillies.
Sprinkle some salt and saute the onions until they start to brown.
Add the ginger and garlic and saute for another minute.
Add the turmeric, red chilli powder, coriander powder and cumin powder. Stir to coat with the oil and toast for a minute.
Add the tomatoes and saute, stirring frequently, until the tomatoes begin to express the oil.
Add the mushrooms, green peppers, and salt to taste.
Stir everything together, lower the heat to a simmer, cover with a lid, and cook for 15 minutes or until the vegetables are tender and have expressed some liquid.
Finish by adding the black pepper and coriander leaves. Turn off the heat.