For the best beef stir-fry, we used sirloin steak. It is a nice, tender cut of meat that marinates and sautés well in a stir fry. It’s a very versatile cut of steak that you almost can’t go wrong with. The downside to sirloin steak is that it can easily get overcooked. For optimal results, stir fry until JUST cooked through. Other cuts of steak that work well for stir fry includes flank steak, skirt steak, and rump steak.