Place the saffron threads in a small bowl with 2 tablespoons of warm water and leave to infuse for 10 minutes. Meanwhile, season the lamb with the salt and black pepper.
Heat 2 tablespoons of the olive oil in a large, heavy-bottomed Dutch oven or deep casserole over medium-high heat. Add the lamb in batches and brown it on several sides, allowing approximately 6–8 minutes per batch. Transfer the browned meat to a plate. Add the remaining tablespoon of oil as needed.
Reduce the heat to medium-low. Add the chopped onions to the same pan and cook for 10–12 minutes, stirring occasionally, until softened and lightly golden. Add the garlic and cook for another minute.
Stir in the cinnamon stick, ground cinnamon, ginger, turmeric, cumin and ground coriander. Cook for approximately 30 seconds, stirring constantly, until fragrant. Do not allow the spices to burn.
Return the lamb and any accumulated juices to the pan. Pour in the saffron together with its soaking liquid, followed by the stock. Stir well, scraping any browned bits from the bottom of the pan.
Bring the liquid to a gentle simmer. Cover with a lid, reduce the heat to low and cook for approximately 1½–2 hours, stirring occasionally, until the lamb is nearly fork-tender. Add a small splash of water or stock if the sauce becomes too thick during cooking.
While the lamb cooks, cover the prunes with warm water and let them soak for approximately 15 minutes. Drain well and set aside.
Once the lamb is nearly tender, stir the honey into the cooking sauce and add the drained prunes. Cover and simmer gently for another 20 minutes, until the prunes are plump and soft and the lamb is completely tender.
Remove the lid and continue simmering for approximately 5–10 minutes if necessary, allowing the sauce to reduce until thick and glossy. Stir carefully so the softened prunes retain their shape. Taste and adjust the salt and pepper. The sauce should have a balanced sweet and savory flavor.
Meanwhile, heat a small dry frying pan over medium-low heat. Add the blanched almonds and toast for approximately 4–6 minutes, turning frequently, until lightly golden. Transfer them to a plate to prevent further browning.
Transfer the lamb, prunes and sauce to a warm serving dish. Scatter the toasted almonds over the top, along with the sesame seeds if using. Finish with chopped cilantro or parsley.
Serve immediately with couscous or warm crusty bread to soak up the fragrant sauce.