In a large mixing bowl, combine warm water, ½ cup salt, sugar and whole peppercorns; stir until dissolved. Add ice until mixture is cooled and measures about 2 qts.; set aside. Arrange chicken breast-side down on a cutting board. Using kitchen shears, cut along one side of the backbone, from the cavity end up to the neck. Repeat on other side of backbone; remove backbone and discard. Turn chicken breast-side up. Using both hands, press down firmly and quickly to crack the breast bone and flatten the bird. Place chicken in a large pot; cover with brine mixture. Refrigerate chicken for at least 1 hr. (up to 24 hrs.). Remove chicken from brine; discard brine. Place chicken breast-side up in a cast iron skillet coated lightly with oil. Rub chicken with oil; season with rub, remaining salt, chopped rosemary, lemon zest and ground pepper. Roast in a preheated 450° oven until a thermometer inserted in the thickest part of the thigh registers 160° (about 40 min.); let stand, covered, for 10 min. (temperature should increase to 165° before serving). Garnish whole bird with rosemary sprigs and lemon slices; serve in the pan with tools for carving at the table.

Tasty Tip:

• Find spatchcocked chickens in the Meat Department.