01 -
Whisk balsamic vinegar, olive oil, minced garlic, Dijon mustard, honey, dried thyme, dried rosemary, and optional red pepper flakes in a medium bowl until fully combined.
02 -
Generously season flank steak on both sides with salt and black pepper to enhance flavor.
03 -
Place steak in a large resealable plastic bag or shallow dish. Pour marinade over steak ensuring even coating. Seal or cover and refrigerate for at least 4 hours, preferably overnight, flipping occasionally for even flavor penetration.
04 -
For grilling, preheat grill to high heat with oiled grates. For pan-searing, heat a cast-iron or heavy skillet over high heat with 1 tablespoon olive oil. For broiling, position oven rack 4-6 inches from the broiler and preheat on high.
05 -
Remove steak from marinade and discard marinade. Pat dry with paper towels. Cook steak 4–5 minutes per side until internal temperature reaches 130–135°F (54–57°C) for medium-rare or 135–145°F (57–63°C) for medium.
06 -
Place steak on a cutting board and tent loosely with foil. Rest at least 10 minutes to allow juices to redistribute.
07 -
Identify the grain of the meat and slice thinly against the grain at a 45-degree angle to ensure tenderness.
08 -
Arrange sliced steak on a platter and garnish with chopped fresh parsley before serving.