Rub both sides of tronchetta with rosemary, fennel seeds and salt; with skin side down, roll tronchetta and tie at 1-inch intervals with butcher’s twine. Let tronchetta stand at room temperature 1 hour. Toss oranges, rosemary, garlic, sage, thyme and pepper in a hotel pan; place tronchetta on top and roast at 450°F until skin is golden brown, about 45 minutes. Reduce oven temperature to 325°F; roast tronchetta until internal temperature reaches 155°F, about 2 hours 45 minutes. Let tronchetta stand 30 minutes; slice into 12 portions. Refrigerate in an airtight container up to 6 days.
Golden Beet Polenta
Toss beets in oil in a hotel pan; cover with foil and roast at 375°F until very tender, about 1 hour. Cool beets slightly and peel; purée beets and cream in a food processor. Heat broth to a simmer in a saucepan over medium-high heat; whisk in polenta. Reduce heat to medium-low; cook until thickened, about 30 minutes, whisking occasionally. Stir in beet mixture, cheese, butter, salt and pepper. Transfer to a hotel pan; hold warm in a steam table for service. Makes about 12 cups.
Heat an oven-safe sauté pan over medium-high heat; add 1 slice tronchetta and sear on both sides, about 4 minutes; add ½ cup leeks and transfer to oven. Roast tronchetta and leeks at 450°F until tronchetta is heated through and leeks are tender and starting to crisp, about 15 minutes. Toast ½ teaspoon fennel seeds in a sauté pan over medium heat until fragrant, about 1 minute, shaking pan occasionally. Add ¼ cup each juice and wine, 1 teaspoon honey and ½ teaspoon chili sauce; cook until reduced to 2 tablespoons, about 3 minutes. Heat 1 cup polenta in a sauté pan over low heat until heated through, about 4 minutes, stirring occasionally. Serve tronchetta with orange-wine reduction and polenta topped with roasted leeks.