Step 1

Toast aniseed in a dry small skillet over medium heat, tossing occasionally, until fragrant, about 3 minutes. Let cool; finely grind in a spice mill or a mortar and pestle. (Alternatively, chop with a knife.)

Step 2

Finely chop salt, grated zest, sugar, chopped rosemary, thyme leaves, pepper, and 4 tsp. aniseed in a food processor.

Step 3

Place turkey, skin side down, on a cutting board. Use a knife to score down long oblong bone in the center of breast. Turn skin side up and press down on breastbone to flatten. You should hear a crack and feel the bones give way. Rub all over with salt mixture; place turkey, skin side up, on a wire rack set inside a rimmed baking sheet and chill, uncovered, 6–18 hours.

Step 4

Preheat oven to 450°. Arrange onions, carrots, celery, garlic, and thyme and rosemary sprigs in a roasting pan. Rinse turkey, pat dry, and place, skin side up, on top of vegetables; let sit at room temperature 30 minutes.

Step 5

Meanwhile, heat oil, orange zest strips, and remaining aniseed in a small saucepan until oil is sizzling, about 2 minutes; let cool slightly.

Step 6

Brush turkey with oil, add ½ cup water to pan, and roast turkey 30 minutes. Reduce oven temperature to 350° and continue to roast, brushing with oil every 20 minutes, until skin is deep golden brown and crisp and an instant-read thermometer inserted into thickest part of thigh registers 165°, about 1 hour longer. Transfer to a platter; tent with foil and let rest at least 30 minutes before carving.