Ingredients

• 1 4–5-pound boneless lamb shoulder
• Kosher salt, freshly ground pepper
• 6 garlic cloves, thinly sliced
• 2 mandarin oranges or tangerines, unpeeled, thinly sliced into rounds
• 1 cup Taggiasca or other fruity, brine-cured black olives, pitted, coarsely chopped
• 2 tablespoons chopped fresh savory or rosemary
• 1 teaspoon crushed red pepper flakes
• 1 1/2 cups beef stock or low-sodium chicken broth
• 1 1/2 cups dry red wine
• 1 cup tomato purée

Instructions

1. Holding knife parallel to work surface, cut lamb lengthwise, following seam where bone was removed and stopping about 1/2" before you get all the way through. Open lamb like a book and season all over with salt and pepper. Close, wrap tightly in plastic, and chill at least 8 hours.
2. Preheat oven to 400°F. Open lamb and arrange garlic on bottom half, leaving a 1" border. Top with orange slices and olives. Sprinkle with savory and red pepper flakes. Close lamb and tie at 1" intervals with kitchen twine.
3. Place lamb on a wire rack set inside a large rimmed baking sheet. Roast until nicely browned, 30–40 minutes. Remove lamb from oven.
4. Reduce oven temperature to 300°F. Carefully transfer lamb to a large heavy ovenproof pot and add stock, wine, and tomato purée. Cover and braise lamb, basting with braising liquid every 30 minutes, until golden brown and fork-tender, 2 1/2–3 hours. Season with salt and pepper, if needed.
5. Transfer lamb to a cutting board and let rest at least 30 minutes before slicing. Serve with braising liquid.
6. DO AHEAD: Lamb can be seasoned 1 day ahead; keep chilled. Lamb can be braised 2 days ahead; cover and chill.