Preheat the oven to 300F. In a small bowl, combine the coriander, cumin, cinnamon, cayenne, turmeric, and cloves. Pat the lamb dry and season all over with salt and pepper
In a large dutch oven, heat the oil until shimmering. Add the lamb and brown all over, about 10 minutes. Transfer to a plate with a slotted spoon. If your pot is smaller, you can work in batches.
Add the onion to the pot and sprinkle with salt. Sauté until translucent, 4 or 5 minutes. Stir in the garlic and spice mixture and cook until fragrant, about 1 minute. Add the tomatoes, broth, bay leaves and lamb.
Bring to a simmer, then cover and transfer to the oven. Cook until the lamb is tender, about 1 ½ hours. Add the cauliflower and continue cooking until cauliflower is tender, another 20 minutes or so.
Remove the bay leaves and stir in lemon zest before serving.
Notes
Storage Information: You can easily make this dish a day or two ahead of serving it. Once cooked and cooled, store in an air tight container in the refrigerator. Gently reheat on the stove or in the oven and serve. Leftovers can be refrigerated for up to 4 days. You can also freeze the stew for several months.