Sprinkle the cauliflower with the chilli powder. Put a steamer on the hob or place a colander in a pan with 5cm water in the bottom and steam the cauliflower for 5 mins until just tender.
Blend all the marinade ingredients in a food processor, rub them over the cauliflower, then leave to marinate for 1 hr.
Cook the cauliflower on a medium-hot barbecue with the lid on until cooked through (check by inserting a small knife into the stem), making sure the cauliflower doesn’t directly touch the flames and burn. (Or heat oven to 220C/200C fan/gas 7 and cook on a baking tray for 10-15 mins until cooked through.)
Put the cauliflower on a plate and coat all over with the yogurt. Zig-zag the green chutney over, then sprinkle the pomegranate seeds, coriander and fried shallots on top.