Skirt Steak
Skirt Steak is a meat ingredient where cut size, trim, and surface moisture matter. Keep the surface dry for browning, cook to the texture the dish needs, and season with control.
Identity
Meat cut
Surface dryness and cut size shape browning.
Meat browns best when the surface is dry and the pan is not crowded. Match the cut size to the method, then season in stages so the dish stays balanced.
Wikimedia Commons
Reference image
Skirt Steak reference image.

Source: Wikimedia Commons
Substitutions
Acceptable
Boneless Rib Eye Steak -> Skirt Steak
1 pound (454g) boneless rib eye steak or skirt steak or store-bought pre-sliced rib eye (see notes)1 tablespoon (15ml) vegetable or other neutral oil
The source lists this as an alternative in the same ingredient row.
Source: Philly Cheesesteaks