Directions. 1  Preheat oven to 450 degrees. 2  Season lamb racks with salt and pepper; coat each evenly with 3 Tbsp pesto. 3  Roast on baking sheet until about 5 degrees less than desired doneness (about 20 min for medium). 4  Transfer lamb to clean platter; let rest 10 min before slicing.
Preheat the oven to 400 degrees F. Using your hands, rub the lamb all over with the lemon juice. Pat the garlic and rosemary evenly all over the surface of the meat. Season the meat with the salt and pepper and place the lamb in a roasting pan. Place the lamb in the oven and roast for 30 minutes.
1 In a large roasting pan combine the red onion, 2 teaspoons oil and garlic in the center of the pan. 2  Place parsley sprigs, rosemary sprigs, and thyme sprigs on top of the onion mixture. 3  Place lamb on top of herbs and drizzle with remaining oil (1 tablespoon). Reduce oven to 350-degrees F. and roast until meat is done (for medium rare meat thermometer inserted into lamb reads 145-degrees F.) about 75 - 90 minutes. 2  Transfer lamb to a cutting board and cover loosely with foil for about 15 minutes before slicing.