According to American Lamb, the amount of time that a lamb fillet should be cooked depends on the cut of meat. A loin or chop should be cooked for seven to 12 minutes. A leg steak, however, should be cooked for 14 to 18 minutes.
In the United States, it is possible to purchase lamb produced in the United States, Australia or New Zealand. American lamb has a slightly milder flavor than its Australian and New Zealand counterparts due to a larger size and primary diet of grains. Lamb, when purchased, should be pink and have a marbled appearance. Lamb fillets should not be stored more than five days and should be kept refrigerated at temperatures less than 40 degrees Fahrenheit.