Now you can put your tasty leftovers to good use to make this beef fried recipe or you can start from square one with uncooked ingredients. Either way, you must use cold leftover cooked rice, otherwise, freshly prepared rice will create a gloppy mess. Flank steak, a tough cut of meat, is traditionally cooked low and slow for many hours using a technique called braising to break down the connective tissue. But in this recipe, it will only get a few minutes of cooking. Marinating will help to tenderize it but it needs to be sliced thinly so it can cook quickly and not toughen up further. In order to do this easily, freeze the steak until it is semi-solid and slice across the grain.