Does anyone know what cut of meat is used for kalbi? Is it a specialty cut?
It is usually made with short ribs and you can use beef or pork.
Skirt steak would be the best cut, although I have to admit that I submitted a food52 contest recipe using flank steak, which works very well but is more expensive. You can also use a flanken cut which is really cheap.
Short ribs, cut thinly lenthwise against the bone. It is also labeled Flanken in non Asian grocers (not to be confused with flank steak, although that is a fine substitute.)