How long do you cook a roast lamb 2.3 kilos?

The cooking time for a roast lamb will vary depending on the size and cut of the meat, as well as the desired level of doneness. As a general guide, you can expect to cook a 2.3 kilo roast lamb for approximately 2 hours and 30 minutes at 160°C (325°F) for medium-rare, or until the internal temperature reaches 60°C (140°F). For well-done lamb, cook for an additional 30 minutes, or until the internal temperature reaches 75°C (165°F).

To ensure the lamb is cooked evenly and to your desired doneness, it's recommended to use a meat thermometer to monitor the internal temperature. Additionally, allowing the lamb to rest for at least 15 minutes before carving will help to ensure the juices are redistributed throughout the meat, resulting in a tender and flavorful roast lamb.