Pat the beef sirloin steak dry with paper towels
Season both sides with salt and black pepper
Let the steak sit at room temperature for 20 to 30 minutes
Heat a skillet, grill pan, or grill over high heat
Add a small amount of oil if using a skillet or grill pan
Place the steak on the hot surface
Cook for 3 to 5 minutes on the first side
Flip the steak
Cook for 3 to 5 minutes on the second side
Check the internal temperature with a meat thermometer
Remove at 125°F for rare
Remove at 130°F to 135°F for medium-rare
Remove at 140°F to 145°F for medium
Add butter, garlic, or herbs during the last minute if desired
Transfer the steak to a plate or cutting board
Rest the steak for 5 to 10 minutes
Slice against the grain
Serve immediately