Preheat the oven to Gas Mark 3, 160ºC (325ºF). Heat a large frying pan. Mix together the paprika, coriander, cumin, cinnamon, turmeric and one teaspoon of pepper in a large bowl. Add the lamb shanks and using your hands rub in the spices. Add a little of the olive oil to the heated pan and quickly brown off two of the spiced lamb shanks. Transfer to a casserole dish with a lid and repeat with the remaining lamb shanks. Meanwhile, place the onion, garlic and ginger in a food processor or mini-blender and pulse until finely minced. Add another tablespoon of the olive oil to the pan, then add the onion mixture and sauté for 3-4 minutes until well softened and coloured from the spices left in the bottom of the frying pan. Pour a little of the stock into the pan, stirring to combine and then tip over the lamb shanks. Add the remaining stock with the tomatoes and honey, stirring gently until evenly combined. Cover with the lid and cook for 2-2½ hours until the lamb shanks are meltingly tender and the meat is ready to fall off the bone. Add a squeeze of lemon juice and season to taste.
Arrange the lamb shanks in wide-rimmed bowls with the couscous to serve.