Put the saffron into a jug, cover with 500ml of boiling water and leave to infuse. Meanwhile, peel and finely slice the garlic and ginger, then place in a large casserole pan over a medium heat with 2 tablespoons of oil, the cumin, cinnamon and ras el hanout. Add the tomato paste, fry for a few minutes, stirring regularly, then pour over the saffron water. Trim and prep the veg, as necessary, then chop into large chunks, adding them to the pan as you go. Tip in the chickpeas (juices and all), roughly chop and add the apricots and preserved lemon, discarding any pips, then season with sea salt and black pepper. Bring to the boil, cover, reduce the heat to low, and simmer for 45 minutes, or until tender, stirring occasionally.
When the veg are almost tender, just cover the couscous with boiling water, season with salt and pepper and pop a plate on top. Leave for 10 minutes, then fluff and fork up. Pick the herb leaves and toast the almonds. Serve the tagine and couscous sprinkled with the almonds and herbs.