Pat the skirt steak dry
Season generously with salt and pepper
Let it sit at room temperature for 20 to 30 minutes
Heat a cast-iron skillet or grill over high heat
Add a small amount of oil if using a skillet
Cook the steak for 2 to 4 minutes per side
Flip only once
Cook to medium-rare or medium for best tenderness
Check for an internal temperature of 130 to 140°F for medium-rare
Remove from heat and rest for 5 to 10 minutes
Slice thinly against the grain
Serve immediately