Instructions

 Grind fennel seeds and peppercorns using spice grinder or mortar and pestle until finely ground. Transfer to food processor and add rosemary, sage, thyme, garlic, and 4 teaspoons salt. Pulse mixture until finely chopped, 15 to 20 pulses, scraping down sides of bowl as needed. Add oil and process until paste forms, 20 to 30 seconds. Cut seven 16-inch lengths and one 30-inch length of kitchen twine and set aside. Measure out 20-inch piece of aluminum foil and crumple into loose ball. Uncrumple foil and place on rimmed baking sheet (crinkled foil will insulate bottom of sheet and minimize smoking during final roasting step). Spray wire rack with vegetable oil spray and place on prepared sheet.
 To remove back, place turkey breast skin side down on cutting board. Using kitchen shears, cut through ribs, following vertical lines of fat where breast meets back, from tapered ends of breast to wing joints (A). Using your hands, bend back away from breast to pop shoulder joints out of sockets (B). Using paring knife, cut through joints between bones to separate back from breast (C).
 Flip breast skin side up. Starting at tapered side of breast and using your fingers to separate skin from meat, peel skin off breast meat and reserve (D). Using tip of chef's knife or boning knife, cut along rib cage to remove each breast half completely (E). Reserve bones for making stock, or discard. Peel tenderloins from underside of each breast (F) and use knife to remove exposed part of white tendon from each tenderloin.
 Lay 1 breast half on cutting board, smooth side down and with narrow end pointing toward your knife hand. Holding knife parallel to cutting board, slice into breast starting where breast becomes thicker (about halfway along length). Stop ½ inch from edge of breast (G) and open to create 1 long piece of even thickness. Repeat with remaining breast half. Transfer all meat to large bowl. Add herb paste and massage into meat to coat evenly.
 Pat exterior of skin dry with paper towels and lay flat, exterior side down, on cutting board with long side running parallel to counter. Remove any loose pieces of fat. Lay 1 breast half on 1 side of skin with butterflied end closest to you. Lay second breast half next to first with butterflied end farthest away from you (H). Spread breast halves slightly apart and lay tenderloins between them with their thin ends overlapping in center (I).
 Using skin as aid, fold up each breast half over tenderloins so skin meets directly over tenderloins. Slip one 16-inch length of twine under roast about 2 inches from 1 end and tie into simple knot, pinching skin closed as you tighten. Repeat tying at opposite end (J). Tie remaining five 16-inch lengths of twine evenly between 2 end pieces. Trim excess twine.
 Tie 1 end of 30-inch length of twine onto loop farthest from you. Working toward you, loop twine over top and around each successive strand until you get to bottom of roast (K). Flip roast and continue looping to bottom of roast (L). Flip roast again and tie off where you started. Sprinkle roast evenly with remaining 2 teaspoons salt; place on prepared rack; and refrigerate, uncovered, for at least 8 hours or up to 2 days.
 Adjust oven rack to upper-middle position and heat oven to 275 degrees. Brush roast with melted butter. Cook until thickest part of roast registers 125 degrees, 1½ to 1¾ hours. Remove roast from oven and increase oven temperature to 500 degrees. When oven is up to temperature, remove twine from roast; return roast to oven; and cook until skin is browned and roast registers 145 degrees, 15 to 20 minutes.
 Transfer roast to cutting board, tent with foil, and let rest for 30 minutes. Slice ½ inch thick and serve.