I'm not sure how it started, but my mom and every other Korean mom I know rub kiwi pulp on thin strips of flanken-style short ribs before dunking the ribs in a sweet soy sauce and garlic mixture, and grilling them to charred perfection. There's an enzyme in kiwi that supposedly breaks down surface meat fibers, and since the ribs are sliced thin (about 1/2 inch), they become very tender throughout.
A little goes a long way though, and if you use too much kiwi, your meat will become mushy in a very unappetizing way. A scant half a kiwi is good for four or five pound of meat. Don't be tempted to use more. And you don't have to use a food processor; just mash the peeled kiwi in your hands as you work it against the meat.
And finally, here is our excellent recipe for Korean Barbecued Short-Ribs! [Welcome to Julie, who we're trying on for size for one of the writer/editor positions... comment away!]