I have a few packages of pre-cut beef labelled only as "stir-fry beef," from a local farm. When I used one package in a stir-fry, it came out very tough. Part of the problem, I think, is that the meat pieces were cut very unevenly by the butcher. Any ideas of what else I might do with this meat to make it more palatable? I know I should probably marinate it for a good while, but will that make up for the uneven cut?