This rolled and tied bird cooks evenly, slices into beautiful disks, and is saturated with the rich herb-and-garlic flavors of porchetta. If you let your butcher do the work of removing the bones, preparing it is remarkably straightforward.
Combine the fennel, juniper, 1 tablespoon plus 1 teaspoon kosher salt and 1 tablespoon ground black pepper in a small bowl and set aside. Combine the pancetta, rosemary, red pepper flakes, garlic and lemon zest in a small food processor and pulse several times to make a coarse paste, scraping down the bowl as needed.
Open the turkey like a book, skin-side down, on a large cutting board. (It should look like an irregular rectangle with the drumsticks on one side and the wings on the other.) Pull off the long, thin tenderloins from the breast, and lay them on the inside of the thigh meat to even out the thickness of the turkey. Sprinkle the inside of the turkey with some of the salt mixture, and top evenly with the pancetta mixture.
Roll up the turkey starting at the edge closest to you, and continue to roll forming a tight log, finishing with the seam-side down. Tie with kitchen string at 1-inch intervals, maintaining as tight a log as possible. Adjust the string to make the drumstick as straight as possible. Tuck the wings behind the turkey’s back and sprinkle the outside with the remaining salt mixture. (The turkey can be prepared to this point up to 1 day in advance.)
Position an oven rack in the lower third of the oven, remove the top racks and preheat the oven to 375ºF. Fit a wire rack into a baking sheet and put the turkey on top. Brush all over with olive oil and turn the turkey seam-side up. Roast until the skin is browned and crisp, about 1 hour. Remove the baking sheet from the oven and carefully flip the turkey using a large spatula.
Return the turkey to the oven and continue cooking until the top is deep golden brown, and an instant-read thermometer inserted into the thickest part of the turkey registers 155ºF, 50 to 60 minutes more. Remove from the oven, tent loosely with foil, and let rest 20 minutes before slicing. (The turkey will continue cooking as it rests.)
Cut off the string with scissors, taking care not to tear the skin. Cut the turkey into 1/2- to 3/4-inch slices and separate the drumsticks and wings. Serve immediately.