Spatchcocked Turkey with Anise and Orange

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.)
Finely chop salt, grated zest, sugar, chopped rosemary, thyme leaves, pepper, and 4 teaspoons aniseed in a food processor.
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. 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.
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.
Meanwhile, heat oil, orange zest strips, and remaining aniseed in a small saucepan until oil is sizzling, about 2 minutes; let cool slightly.
Brush turkey with oil, add 1/2 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.