Roasted Lamb Shoulder Stuffed with Merguez and Swiss Chard

INGREDIENTS

• 1 (4-pound) boneless lamb shoulder
• 2 tablespoons dried oregano
• 2 teaspoons coarsely ground black pepper
• 3 tablespoons extra-virgin olive oil
• Coarse salt
• 5 tablespoons canola oil
• 2 lemons, halved crosswise
• 6 shallots, halved
• 1 head garlic, halved crosswise
• 8 sprigs fresh thyme
• 3 sprigs fresh rosemary
• Juice of 1/2 lemon
• Coarse salt and freshly ground black pepper
• 1 bunch Swiss chard, leaves and stems separated
• 4 tablespoons extra-virgin olive oil
• 1 small onion, cut into 1/4-inch pieces
• 2 cloves garlic, finely chopped
• 1/2 pound merguez sausage, casings removed
• 1 teaspoon finely chopped fresh rosemary
• 2 teaspoons chopped fresh thyme
• 1/2 cup panko (Japanese breadcrumbs)
• Zest of 1 lemon
• 2 tablespoons chopped fresh mint
• 2 tablespoons chopped fresh flat-leaf parsley