Pancetta and Rosemary Turkey Breast with Roasted Potatoes and Apple Relish

• 1 boneless turkey breast half (with skin), about 3 pounds, butterflied
• 1 tablespoon plus 2 teaspoons finely chopped fresh rosemary leaves, divided
• 1 tablespoon finely chopped fresh sage leaves
• 2 teaspoons finely grated lemon zest
• 2 large garlic cloves, minced or pushed through a press
• Kosher salt
• Freshly ground black pepper
• 4 ounces thinly sliced pancetta
• 1 tablespoon unsalted butter, melted

Relish

• Vegetable oil
• 1 tablespoon finely chopped fresh sage leaves
• ½ large yellow onion, cut into ½-inch dice (about 1 cup)
• 2 sweet-tart apples, such as Pink Lady or Jazz, about 1 pound, unpeeled, cored, and cut into ½-inch dice (about 3 generous cups)
• 2 medium celery ribs, thinly sliced
• ½ cup water
• 3 tablespoons fresh lemon juice
• 2 tablespoons honey
• 1 teaspoon cider vinegar

• 2 pounds new red potatoes, about 1½ inches in diameter, each cut in half