Prep for Perfection: About 10 minutes before you're ready to cook, pull the steaks from the fridge. Use paper towels to pat them completely dry—this is the secret to achieving that incredible, deep-brown crust.
Season every surface generously with salt and freshly ground black pepper.
Get That Pan Screaming Hot: Place a large cast-iron skillet or heavy-bottomed pan over medium-high heat.
Add the olive oil and butter.
Let them heat up until the butter is melted and the fat begins to shimmer beautifully.
Time for the Sizzle: Gently lay the seasoned steaks in the hot pan, being careful not to overcrowd it. If necessary, cook in two batches to ensure each steak gets direct contact with the heat. You should hear a satisfying sizzle the moment the meat hits the pan.
Sear, Don't Stir: Let the steaks cook, completely undisturbed, for 3-5 minutes on the first side to develop a gorgeous crust.
Flip and cook for another 3-5 minutes on the second side. For a perfect medium-rare, use a meat thermometer to check for an internal temperature of 130−135°F (54−57°C).
The All-Important Rest: This step is non-negotiable!
Transfer the seared steaks to a cutting board and let them rest for 5-10 minutes. This allows the juices to redistribute throughout the meat, guaranteeing every bite is tender and succulent.
Slice and Serve: After resting, thinly slice the flank steak against the grain.
Arrange the beautiful slices on your plates, top with a generous spoonful of vibrant pesto, and serve immediately.
Don't be afraid to press the steaks down gently with a spatula for the first 30 seconds of cooking. This ensures the entire surface makes contact with the pan, resulting in an even, golden-brown crust.
