Heat your oven to 200°C/Fan 180°C/Gas 6. Remove the pork from its packaging and pat dry. Leave to come to room temperature.
Peel and grate the garlic into a large bowl. Finely chop the dates, discarding the stones. Zest the lemon. Add 2 tsp ras el hanut to the bowl and tip in the couscous. Mix everything together with a large pinch of salt.
Pop the joint into a roasting tin. The pork shoulder is rolled, so there will be a pocket in the middle of the joint. Using a spoon and your fingers, stuff as much of the spiced date couscous into this space as you can, filling the joint from both ends. The moisture from the roasting pork will cook the couscous. If there is any left over, set aside.
Sprinkle 1 tsp salt and 1/2 tsp ras el hanut on to the skin. Rub it in, making sure you work it into the slashes. Slide it into the oven and roast for 40 mins-1 hr till the skin is crisp, bubbled and well browned.
Turn the oven temperature down to 160°C/Fan 140°C/Gas 3. Loosely cover the roasting tin with foil. Slow cook the pork for 3 hrs, removing the foil for the final 30 mins.
Allow the pork to rest for at least 30 mins. The pork should be meltingly soft and the skin crispy. If the skin isn’t crisped up enough, cut the skin from the pork. Pop under a hot grill for 2 mins.
If you did have any leftover stuffing, pour over enough boiling water to just cover it while the pork is resting. Within 30 mins it will have absorbed the water and be tender.
Carve the pork and serve with spoonfuls of the spiced stuffing and lemon wedges to squeeze over.