Put peas & water in a covered pot & bring to a boil. Simmer for 2 minutes, turn off heat & let steep for 1 hour.
Heat oil & when hot put in the cumin seeds & cinnamon stick. Let then sizzle for a few seconds. Add onions & garlic & stir-fry until the onions start to turn brown at the edges. Put in the mushrooms & stir-fry until they begin to wilt. Add the tomatoes, coriander, cumin, turmeric & cayenne. Stir & cook for 1 minute. Cover, turn heat to low & cook for 10 minutes. Turn off heat.
Bring peas back to the boil, simmer for 20 to 30 minutes. Then add the cooked mushrooms & spices along with the remaining ingredients. Simmer, uncovered on low heat for 30 minutes. Stir occasionally.
Remove cinnamon stick & serve.