How to Make It
Preheat the oven to 425°. In a roasting pan large enough to hold the lamb, whisk the chicken stock with the wine, lemon juice, honey, allspice, cloves, coriander, paprika, oregano, thyme and peppercorns. Add the onions, garlic and jalapeños in an even layer. Season the lamb all over with salt and pepper and place it in the roasting pan, fat side up.
Braise the lamb, uncovered, for 45 minutes until it just starts to brown. Reduce the oven temperature to 325° and braise for about 2 hours and 30 minutes longer, until the meat is nicely browned and starting to pull away from the bone. Transfer the lamb to a carving board and let stand for 10 minutes.
Strain the braising liquid into a medium saucepan and skim off the fat. Boil the liquid until slightly reduced, about 10 minutes. Season the jus with salt and pepper; keep warm.
Combine all of the ingredients in a food processor and puree until smooth. Season with salt and pepper. Transfer to a bowl.
Combine all of the ingredients in a medium bowl and toss well. Season with salt and pepper.
Cut the strings off of the lamb and carve the meat into 1/2-inch-thick slices. Arrange the lamb on a bed of couscous on a large, deep platter. Drizzle the jus and spiced yogurt over the lamb, top with the herb salad and serve.
The lamb can be refrigerated with its reduced jus overnight. Reheat and slice before serving.