To make the Marinade: Zest the lemon with a fine grater, taking care to only remove the yellow peel¿the white pith beneath it is bitter. Use the lemon juice for cocktails, or splash a bit into the marinade if you really love citrus. Mix all the marinade ingredients together.
To make the Stuffing: Mix the stuffing ingredients together.
To prepare the Lamb: Cut the rack in 1/2 crosswise so that each piece contains 4 chops. Insert a long, skinny knife into 1 end of the meat and push it through until the tip emerges from the other end. Then, remove the knife and use the handle of a wooden spoon to ream out a 1/2-inch hole, forming a tube through the 4 chops. With your fingers, press half the stuffing into the rack, making sure it's distributed evenly. Repeat with the other half of lamb.
Place the lamb in a zipper baggie, spoon the marinade onto the meat, and rub it in a little bit. Marinate for at least 1 hour, preferably 4 hours.
Preheat the oven to 425 degrees F.
Roast the chops for 25 minutes for medium rare, or until an instant-read thermometer inserted into the thickest part of the meat registers 135 degrees F. Let the meat rest for 10 minutes (during which they continue cooking, and the juices run back to the center). Slice into individual chops, if you like, fan across the plate, garnish with a rosemary sprig, and serve.