As with any beef stir fry, you need a cut of steak that can withstand quick, high-heat cooking while staying tender and juicy. The best steak cuts for lomo saltado are sirloin, strip steak, ribeye, and filet mignon.  Flank and skirt steak also work, but they aren’t as naturally tender. It can help to marinate these cuts in a steak marinade to help them stay moist and juicy during the cooking process.