Instructions

for the crown roast

Set wire rack in rimmed baking sheet. Spray rack with vegetable oil spray. Combine garlic, thyme, and oregano in small bowl. Transfer 1 tablespoon garlic mixture to second small bowl and stir in oil; refrigerate garlic-herb oil until needed for brushing. Stir salt, pepper, and lemon zest into remaining garlic mixture.
Pat roasts dry with paper towels. Place 1 roast fat cap side up on cutting board perpendicular to counter edge. Using boning knife, cut guideline 1½ inches from tips of bones (all the way down to bones), down length of rack. Running knife along bones, cut and scrape meat off tops of bones. Carve out meat between exposed bones, cutting and scraping closely along bones to remove any large pieces of meat (bones needn't be perfectly clean). Cut any large pork trimmings into rough 2-inch pieces and refrigerate 1 cup trimmings for pan sauce; discard remaining trimmings or reserve for another use.
Flip roast fat cap side down, parallel to counter edge with tips of bones facing away from you. Cut slits into loin in between every 2 bones, about 1 inch deep and 3 inches long (4 to 5 slits per roast).
Position roast with bones pointing up and butterfly roast by slicing into center of loin, stopping 1 inch from bottom to keep roast intact, down length of roast. Repeat steps 2 through 4 with second roast.
Open roasts so they lie flat and rub interior of each roast with 2½ tablespoons garlic-salt mixture (5 tablespoons total). Fold halves together (returning roasts to original shape). Cut one 18-inch length of kitchen twine per slit; tie roasts tightly with twine around each slit to secure roasts.
Place one 4-foot-long piece of twine parallel to counter edge. Center 1 roast fat cap side up on twine parallel to counter edge. Place second roast on top of first roast, fat cap side down, with bones facing same direction. Bring ends of twine up and around both roasts and tie tightly. Stand assembled roast with bones pointing up. Rub remaining 10 tablespoons garlic-salt mixture all over roast.
Crumple large piece of aluminum foil into 3-inch ball. Gently separate roasts to form oval shape and tuck foil ball in center. Bend ends of each roast inward to form rounded shape, adjusting twine as needed to keep it taut. Tie second 4-foot-long piece of twine around bones to cinch into crown shape. Transfer tied roast to prepared wire rack and refrigerate, uncovered, for at least 12 hours or up to 24 hours.
Adjust oven rack to middle position and heat oven to 250 degrees. Insert thermometer probe horizontally into thickest part of meat, about 1 inch below bones. Roast until internal temperature reaches 135 degrees, 2½ to 3 hours.
Remove roast from oven and remove thermometer probe. Increase oven temperature to 450 degrees. Brush roast all over with reserved garlic-herb oil. Once oven has preheated, return roast to oven and roast until well browned, 15 to 20 minutes. Remove roast from oven and tent with foil. Let rest for at least 30 minutes or up to 1 hour.

for the pan sauce

While roast rests, heat oil in large saucepan over medium-high heat until just smoking. Add reserved pork trimmings and cook, stirring occasionally, until pieces are browned all over and fond has formed on bottom of saucepan, 5 to 7 minutes. Stir in shallot and garlic and cook until lightly browned, about 2 minutes. Stir in broth and wine, scraping up any browned bits. Bring to boil over high heat and cook until reduced by three-fourths, about 15 minutes.
Strain liquid through fine-mesh strainer set over measuring cup (you should have about 1 cup); discard solids. Return liquid to now-empty saucepan and simmer over medium heat as needed to reduce to 1 cup. Off heat, whisk in butter, 1 piece at a time, until incorporated (sauce should have consistency of creamy salad dressing). Whisk in thyme and vinegar. Season with salt and pepper to taste. Cover to keep warm.
Transfer roast to platter. Remove twine and slice meat between bones. Serve with sauce.