In a large pot, heat the oil over medium-high heat until it shimmers. Add the lamb, onion, parsley, and carrots, and cook, stirring occasionally, until the lamb begins to brown and the vegetables start to soften. Once the lamb has lost most of its pinkness and the vegetables are tender, it's time to infuse the dish with aromatic spices. Sprinkle in the cumin and coriander, stirring until the fragrant spices permeate the air. Then, introduce the chopped tomatoes, chicken broth, harissa paste, saffron threads, and chickpeas, allowing the flavors to meld together as the mixture comes to a gentle simmer.