Flavorful Steak Marinade

1. Finely chop the garlic and the rosemary.
2. In a mixing bowl, combine the balsamic vinegar, soy sauce, dark brown sugar, and olive oil.
3. Add the minced garlic, chopped rosemary, kosher salt, ground black pepper, and red pepper flakes into the bowl and mix everything well.
4. Place the steak in a zip-lock bag and pour the marinade over it. Seal the bag and ensure the steak is well coated.
5. Refrigerate the steak for at least 6 hours to let the flavors soak in.