Preheat your oven to 375°F (190°C).
Pat the lamb shoulder dry and season it with salt, pepper, ground cumin, ground coriander, and ground cinnamon.
In a heavy, oven-safe pot or Dutch oven, heat a drizzle of olive oil over medium-high heat. Sear the lamb on all sides until browned.
Add the minced garlic to the pot and let it sauté briefly until fragrant.
Reduce the heat to low, cover, and allow the lamb to slowly cook for about 1.5 to 2 hours until it becomes tender.
While the lamb is slow-cooking, prepare the vegetables. Peel and roughly chop the carrot, parsnip, and red onion into uniform pieces.
Toss the vegetables with a bit of olive oil, salt, and pepper, and spread them onto a baking sheet.
Place the vegetables in the oven and roast for 25-30 minutes or until tender and lightly caramelized, stirring halfway through.
Once both the lamb and vegetables are cooked, plate a portion of slow-cooked lamb alongside a generous serving of roasted root vegetables.
Finish with an optional drizzle of extra virgin olive oil if desired, and serve warm.