Leave fresh lamb and mutton in its original wrapping, over-wrap with foil to keep meat juices from contaminating other food, and store in the coldest part of the refrigerator. Refrigerate no more than two to four days for small cuts, four to five days for large cuts, and one to two days for stew meat or ground lamb or mutton. To keep lamb and mutton longer than that, wrap in foil or enclose in freezer bags and store in the freezer. Generally, the larger the cut the longer it keeps in the freezer; stew meat and ground lamb and mutton and keep for three to four months; roasts and chops for six to nine months. Defrost frozen lamb or mutton in the refrigerator. Steaks and chops take about 24 hours; roasts two to three days, depending on the size. Bring the meat to room temperature for 30 minutes before cooking. To quick-thaw, separate steaks and chops and place them on a microwavable platter in the microwave oven for 7 to 11 minutes, depending on size and number; turn the meat halfway through the process. Place large roasts or legs in a baking dish and defrost for 18 to 32 minutes, depending on size. Turn halfway though thawing time. Place ground meat in a shallow baking dish, cover, and defrost six to eight minutes, breaking up turning the meat several times.