For the Lamb:
1 Using a sharp knife, score the top and bottom of the lamb leg in a crosshatch pattern. Drizzle with 2 tablespoons avocado oil and season generously all over with salt and pepper. Transfer the lamb onto a sheet pan lined with a wire rack and refrigerate, uncovered, for 1 hour to overnight. The longer it marinates, the better the flavour.
2 In a dry pan, combine the coriander seeds and cumin seeds. Place the pan over medium heat and cook, stirring often, until the spices are fragrant and warmed through, around 4 minutes. Transfer the spices to a mortar and pestle or spice grinder and grind to a fine powder. Add the smoked paprika, paprika and oregano and stir to combine. Set aside.
3 Preheat your oven or Traeger grill to 350F.
4 Preheat a stove-top safe roasting pan over medium-high heat (see notes for alternative pans). Add 1 tablespoon avocado oil and heat until shimmering. Carefully add the lamb and cook, undisturbed, until browned, around 6 minutes. Flip and repeat on each side until the lamb is seared all over, around 18 more minutes total. Transfer the lamb to a tray and set aside.
5 Add the onions to the pan and season with ¼ teaspoon salt. Cook, stirring and lifting any brown bits off the bottom of the pan, until the onions are just softened, around 5 minutes. Add the garlic and spice blend and cook, stirring, until fragrant, 1 minute. Add the harissa paste and cook, stirring to incorporate. Add the beef broth and cook, lifting any brown bits off the bottom of the pan. Return the lamb to the pan, fattier side-up, and add the water. Cover the lamb with a sheet of crumpled parchment paper, then tightly cover the pan with foil, crimping the edges to prevent steam from escaping.
6 Transfer the roasting pan to the oven or Traeger grill and cook, basting with the liquid once every hour, until the lamb is fork-tender, around 3 hours total. If it is still not tender after 3 hours, continue cooking and checking every 30 minutes.
7 Remove the foil and parchment paper and return the lamb to the oven or Traeger grill. Raise the heat to 450F and cook until the lamb is deeply browned and easily falling off the bone, around 30 more minutes. Transfer the lamb to a serving platter, taste the gravy for seasoning and adjust with salt and pepper as desired. If the gravy is too loose, place the pan over medium-low heat and gently simmer it until reduced to your desired consistency. If the gravy is too thick, loosen it with some water or beef stock.
8 Serve the lamb with the gravy, quick pickles, a side of basmati rice and vegetables of choice.
For the Quick Pickles:
10 In a saucepan, combine the water, vinegar, honey and salt. Place over medium heat, bring the liquid to a steady simmer and stir to combine.
11 Add the onions, cucumbers and dill to a large mason jar and push them down as much as possible. Pour in the hot liquid so it reaches the top of the jar and seal with a lid. Set aside in a warm spot on your counter for at least one hour or until cooled. The pickles can be refrigerated up to 1 week.
