How Long to Cook Steak Fajita Strips (Skirt or Flank, Sliced Against the Grain) in the sheet pan
Specification: 1.5 lb skirt or flank steak sliced against the grain into 1/2-inch strips, tossed with fajita seasoning and 2 tbsp oil, mixed with sliced bell peppers and onions in a single layer
3-Step Execution Protocol
Preheat oven to 450°F (232°C). Arrange steak fajita strips (skirt or flank, sliced against the grain) (1.5 lb skirt or flank steak sliced against the grain into 1/2-inch strips, tossed with fajita seasoning and 2 tbsp oil, mixed with sliced bell peppers and onions in a single layer) on a parchment-lined sheet pan in a single layer.
Cook for 10–14 mins. Flip at the 7-minute mark for even browning.
Pepper edges are blistered black in spots, onions have gone translucent with charred tips, and steak strips have deep-brown crust on the outside with visible pink pull-back at the cut edges — probe a thick strip and pull when it reads 130–145°F depending on preferred doneness. Confirm internal temperature reaches 145°F (63°C) with a 3-minute rest for medium; pull at 130°F for medium-rare. Rest for 3 minutes before serving.
USDA FSIS Safe Minimum Internal Temperatures chart lists 145°F for beef whole muscle (steaks, roasts) with a 3-minute rest. Skirt and flank strips reach 130°F medium-rare in 7–9 minutes at 450°F and 145°F medium in 10–14 minutes; the safety floor is comfortably met at either pull if the meat is not ground and comes from an intact whole muscle.