Pat the skirt steak dry
Season both sides with salt and pepper
Let it sit at room temperature for 20 to 30 minutes
Heat a cast-iron skillet or grill until very hot
Add a small amount of oil if using a skillet
Cook the steak for 2 to 4 minutes per side for medium-rare
Flip only once
Check for desired doneness with a thermometer if needed
Remove from heat and rest for 5 to 10 minutes
Slice thinly against the grain
Serve immediately