1. Finely chop tomatoes and onion, store separately
2. Cut button mushrooms into 4 quarters
3. Make a paste of ginger and garlic
4. Finely chop fresh coriander leaves
5. Heat oil in a heavy bottomed non-stick pan
6. Add cardamom pods and black peppercorns, saute for few seconds.
7. Add onion and saute till translucent about 2 mins.
8. Add salt, ginger-garlic paste, turmeric, chilli and cumin powders, saute for a minute till the raw flavours leave.
9. Add the tomatoes and water, cook to one boil.
10. Lower heat and cook till tomatoes are mashed up to a soft, smooth paste; about 10 mins whilst stirring continuously
11. Add the mushrooms, cover and cook for about 20 mins on low heat.
12. Serve with rice or naan, garnished with chopped coriander leaves.