1. Trim the larger leaves from the cauliflower (fine to keep the smaller leaves). Place in a stockpot. Pour the stock over.
2. Place a lid on top. Bring to the boil and cook for 5 minutes.
3. Mix the passata, harissa, pomegranate molasses and garlic in a baking dish.
4. Add the cauliflower. Gloss the cauliflower with olive oil. Season with freshly ground pepper and sea salt. Roast in an oven heated to 200C/Gas mark 6 for 25-30 minutes or until the cauliflower is golden and the sauce has thickened.
5. Crush the walnuts and seeds to make the dukka. Sprinkle over the roasted cauliflower.
6. Finely chop the parsley and dust it over the dish. Quarter the cauliflower and serve with the sauce.