Heat the oil in a large, heavy-bottomed casserole.
Fry mushrooms on relatively high heat, stirring often, until mushrooms are well browned and all the juices have evaporated.
Remove with a slotted spoon and set aside.
Add onions, ginger, garlic and chillies to the casserole and fry gently for another 6 minutes.
Add curry powder and cook for another minute or two on high heat.
Add the remaining vegetables as well mushrooms and any reserved liquid.
Cook on medium heat for two or three minutes, gently stirring so that the vegetables do not catch.
Cool down completely, bottle and keep in the refrigerator.