Step 1

Heat a large cast-iron skillet over medium-high heat for 20 minutes.

Step 2

For the steakhouse spice mix: Mix together the peppercorns, garlic, onion, parsley, dry mustard and red pepper flakes in a small bowl.

Step 3

For the burgers: Gently toss together the chuck and sirloin in a large bowl, making sure not to overwork the mixture. Form the beef into four 3/4-inch-thick patties, each about 4 inches in diameter. Sprinkle them generously with salt and a few grinds of pepper.

Step 4

Spread the steakhouse spice mix evenly on a plate. Coat both sides of the patties with the mixture.

Step 5

Place the patties in the hot skillet; do not press down with a spatula. Cook until the patties are seared and browned on one side, about 3 1/2 minutes, then flip and top each patty with one-quarter of the butter. Cook on the second side until browned and the burgers are medium-rare, about 3 1/2 minutes more.

Step 6

Assemble the burgers using your favorite buns, toppings and condiments.

Step 7

Copyright 2016 Television Food Network, G.P. All rights reserved.