1. Roast: In a small skillet over medium-high, toast coriander seeds until dark brown and fragrant, 3 minutes. Grind in a spice grinder, or crush with a mortar and pestle.

2. Place racks of lamb, fat-side down, on a work surface. Cut one-third of the way through flesh between each rib bone. (This will allow racks to fan open into a crown shape.) Stand racks upright, with fat sides touching. Thread a trussing nee- dle with kitchen twine, and run it horizontally through meat just below last rib bone on one rack, and straight through meat of opposite chop. Form a half-circle by pulling ends of twine together as tightly as possible; tie. Repeat process on opposite ends of racks to finish crown. Where racks are joined, tie rib bones together. Crown can be made up to a day in advance and stored, uncovered, in the refrigerator. (Or just ask your butcher to pre- pare the crown.)

3. Stir together ground coriander, lemon zest, garlic, thyme leaves, oil, 4 teaspoons salt, and 1 teaspoon pepper until a paste forms. Spread mixture evenly over roast. Let stand at room temperature 1 hour.

4. Preheat oven to 425 degrees with rack in bottom third. Place lemon wedges, thyme sprigs, and broth in a roasting pan. Place a flat rack over lemons, then center lamb on rack. Roast until a thermometer inserted into thickest part of roast (near but not touching bones) reads 140 degrees for medium-rare, 35 to 40 minutes. (Prepare pilaf while roast is in oven.) Transfer lamb to a platter; let stand 15 minutes. Remove rack, lemon wedges, and thyme from pan, reserving pan for gravy.

5. Pilaf: Heat a large saucepan over medium-high. Swirl in 2 tablespoons oil. Add bulgur, rice, and onion; season with 1 1/2 teaspoons salt. Cook, stirring frequently, until mixture has a nutty aroma and rice turns golden in places, 4 to 5 minutes. Stir in broth and 1 1/4 cups water. Bring to a boil, then reduce heat to low, cover, and simmer until liquid has evaporated and bulgur is tender but still slightly chewy, 10 to 12 minutes. Remove from heat; let stand 5 minutes. Uncover and fluff with a fork, then stir in parsley, pine nuts, currants, lemon juice, and remaining 2 tablespoons oil. Spoon pilaf into center of finished crown roast on platter, if desired.

6. Gravy: While lamb is resting, place roasting pan across two burners on medium-high. Add 1 1/2 cups broth; bring to a boil. In a small bowl, whisk remaining 1/4 cup broth with flour, then whisk into pan. Continue to boil, scraping up browned bits from bottom of pan, until gravy thickens slightly, 2 to 3 minutes. Remove from heat; stir in butter until melted and combined. Strain gravy through a sieve and serve, with lamb and pilaf.