Roasted Leg of Lamb

INGREDIENTS

• 1 bone-in leg of lamb, aitchbone removed by butcher (7 to 8 pounds)
• 2 tablespoons coarse salt
• 2 teaspoons freshly ground pepper
• 2 tablespoons minced garlic
• 2 tablespoons chopped fresh rosemary leaves, plus sprigs for garnish
• 2 tablespoons Dijon mustard
• 2 tablespoons extra-virgin olive oil
• 1 cup chicken broth or water
• 2/3 cup dry red wine
• 1 1/2 cups chicken broth, divided
• 1 tablespoon plus 1 teaspoon all-purpose flour