Break up the cauliflower into florets, throwing away the stalk. Bring a large pot of salted water to the boil and pop in the cauliflower. Boil for 5 minutes then drain thoroughly. Dry the pot and set over a low heat. Pour in the oil and add the butter. When this has melted, gently fry the onion for about 10–15 minutes, stirring until soft and translucent. Stir in the garlic and ginger, and continue cooking for 5 minutes, before adding the spices, a good grind of pepper, and stirring through for a minute.