Bring the stock, orange juice and zest to a boil in a pot. Add couscous, cranberries, almonds and butter and bring back to boil. Cover, remove from heat, and let stand 5 minutes. Mix in mint and season with salt and pepper. Cool to room temperature.
Preheat the oven to 350 degrees F. Place the roast in a roasting pan; season with salt and pepper. Spoon the couscous mixture into the centre the roast, tightly packing it in and allowing it rise just above the top of the meat. Place any remaining couscous into a lightly buttered casserole, and then cover and set aside. Cover top of the roast with foil to prevent couscous from drying out and bones from scorching. Roast 2 hours. At this point, put casserole of couscous in the oven and roast it and the pork 30 minutes more, or until internal temperature of the meat has reached 165 degrees F. Let roast rest 10 minutes before slicing. Serve with apple sauce or gravy made from the juices in the pan.