Broiled Black Pepper Sirloin Steak

Preheat oven to broil.

Place 12-inch cast-iron skillet under broiler for 2 minutes.

Brush olive oil onto steak. Season both sides of steak generously with salt and freshly cracked black pepper.

Add the steak to the heated pan and broil for 8 1/2 minutes.

Transfer steak to a plate to rest. Heat steak pan on the stovetop over medium heat.

Add onions and butter. Stir and cook until browned, about 6 minutes. Pour in vinegar and stir to scrape up browned bits on bottom of the pan. Let vinegar simmer until reduced, just about 1 minute.

Pour any steak juices from the resting steak into the pan. Transfer the steak to a cutting board and slice into 1/4-inch slices. Lay the steak slices on a platter and pour the sauce over top and serve.