Frozen lamb can be cooked without defrosting. Cooking time varies depending on the cut of lamb. Frozen lamb should generally be cooked an additional one-third of the time called for in the recipe. Using a meat thermometer is vital to ensure the lamb is cooked to a safe temperature.
Rare lamb should have an internal temperature of 135 degrees Fahrenheit, and medium lamb should have an internal temperature of 160 degrees Fahrenheit. Well-done lamb should reach 170 degrees Fahrenheit internally. After the lamb is done, it is best to wait 10 to 15 minutes before carving it. Lamb is often seasoned with rosemary and thyme and served with mint jelly.