01 -
Finely mince the garlic cloves and rosemary sprigs until well chopped.
02 -
In a medium bowl, combine balsamic vinegar, soy sauce, brown sugar, and olive oil. Stir until sugar begins to dissolve. Add the minced rosemary, garlic, salt, black pepper, and red pepper flakes. Mix thoroughly.
03 -
Transfer the marinade to a zip-lock bag, add the steak, and seal. Massage the bag to ensure the steak is completely coated. Refrigerate for 6 hours to allow flavors to penetrate the meat.
04 -
Remove the steak from the marinade and pat it completely dry with paper towels to ensure proper searing.
05 -
Heat a tablespoon of olive oil in a heavy skillet over medium-high heat. Cook the steak until the exterior develops a caramelized crust and the interior reaches desired doneness (approximately 3-4 minutes per side for medium-rare).