Put the saffron into a jug, cover with 500ml of boiling water and leave to infuse.
Heat the oil in a large casserole pan and saute the diced onion for 8 - 10 minutes or until beginning to soften.
Add the garlic, ginger, cumin, cinnamon and ras el hanout to the pan and cook for 2 minutes to bring the spices to life.
Add the tomato paste and saffron water to the pan before adding the vegetables and chickpeas, preserved lemon and raisins.
Season with sea salt and black pepper.
Bring to the boil, cover, reduce the heat to low, and simmer for 45 minutes, stirring occasionally.
Once the vegetables are tender, remove from the heat and sprinkle over the herbs, toasted almond flakes and pomegranate arils.
Serve the tagine over couscous.