Pat your 2 lb flank steak completely dry with paper towels—moisture prevents proper searing and browning. Place the meat on a cutting board and score the surface lightly in a crosshatch pattern to help the marinade penetrate deeper into the muscle fibers.

Combine all marinade ingredients in a bowl: olive oil, balsamic vinegar, minced garlic, Dijon mustard, dried rosemary, thyme, paprika, black pepper, sea salt, red pepper flakes, lemon juice, soy sauce, and Worcestershire sauce. Whisk thoroughly for 30 seconds until the mustard fully incorporates and binds the mixture into an emulsion.

Place your juicy grilled flank steak in a gallon-sized ziplock bag and pour the complete marinade over it, pressing out excess air. Massage the meat firmly for 2 minutes, ensuring marinade reaches all surfaces including edges and scored areas. Refrigerate for exactly 10 minutes—this timing allows flavor absorption without over-softening the muscle structure.

Preheat your grill to 450°F for 8–10 minutes while the steak finishes marinating. Use a two-zone setup with high heat on one side; this flank steak grilled method gives you options for temperature management. Once grill grates are smoking slightly, oil them with high-heat vegetable oil on a folded paper towel to prevent sticking and ensure even browning.

Remove the steak from the bag and let excess marinade drip off for 15 seconds—too much liquid causes steaming instead of searing. Place it on the hot side of the grill for exactly 6 minutes without moving it, allowing a deep brown crust to form through the Maillard reaction. Flip once and grill the second side for 5–6 minutes until the internal temperature reaches 130–135°F for medium-rare doneness.

Transfer the grilled steak to a cutting board and rest it for 5 full minutes uncovered—this critical step allows muscle fibers to relax and reabsorb juices. Do not cover with foil because steam will soften the crust you worked to develop. The internal temperature will rise approximately 3–5°F during resting through carryover cooking.

Slice the rested steak against the grain at a 45-degree angle into ½-inch strips—cutting perpendicular to the muscle fibers shortens them dramatically, maximizing tenderness. Arrange slices on a warm platter and spoon any accumulated board juices over the top for enhanced moisture and flavor.