Cut from the Plate, the inside skirt is a long, thin, affordable muscle that offers good flavor and absorbs marinades well. It is cheaper than the outer skirt, which is considered to be a more center-of-plate cut. It has a prominent muscle grain, similar to the outer skirt & flank steak, so it should be thinly sliced against the grain and cooked no further than medium rare for optimal tenderness.
Inside skirt steaks are the traditional cut of choice for fajitas, but flank steaks & cheaper flap meat are also used. These skirt steaks are sold peeled – their surface membranes and fat have been removed for easier preparation.