This recipe strikes a balance between ease and elegance, much like those simple yet hearty meals I used to whip up for my college friends. Here’s how you can recreate that magic:

1. Remove the flank steak from the refrigerator about 30 minutes before cooking to allow it to reach room temperature.
2. In a small bowl, mix together olive oil, minced garlic, chopped rosemary, balsamic vinegar, and Dijon mustard. This marinade will infuse the steak with a robust flavor profile.
3. Pat the steak dry with paper towels and season both sides generously with kosher salt and black pepper.
4. Heat a large skillet over medium-high heat until it’s hot but not smoking. Add the steak to the pan and sear for about 3-4 minutes on each side for medium-rare. Adjust the cooking time to your preferred level of doneness.
5. Once the steak is cooked to your liking, transfer it to a cutting board and let it rest for about 5 minutes. Resting is crucial—it allows the juices to redistribute, resulting in a more tender bite.
6. Slice the steak against the grain into thin strips and serve with a squeeze of lemon, if desired.

Remember, cooking is a journey. If you find yourself with a slightly overcooked piece, fear not. A sprinkle of flaky sea salt and a drizzle of olive oil can work wonders.