In a mixing bowl, whisk together the marinade ingredients: soy sauce, Worcestershire sauce, olive oil, balsamic vinegar, minced garlic, honey or brown sugar, and red pepper flakes (if using).

Place the flank steak in a resealable plastic bag or shallow dish. Pour the marinade over the steak, ensuring it's evenly coated. Seal the bag or cover the dish and refrigerate for at least 2 hours, or up to overnight for deeper flavor.

Preheat your Traeger grill to 225°F using hickory, oak, or mesquite wood pellets. Allow the grill to heat for 15 minutes with the lid closed.

Remove the steak from the marinade and pat it dry with paper towels. Season both sides with kosher salt, black pepper, garlic powder, and smoked paprika.

Place the steak directly on the grill grates and smoke for 45–60 minutes, or until it reaches an internal temperature of 120°F for medium-rare.

Increase the Traeger temperature to 450°F. Sear the steak for 1–2 minutes per side until it develops a caramelized crust and reaches an internal temperature of 130–135°F for medium-rare or 140–145°F for medium.

Remove the steak from the grill and let it rest on a cutting board for 10 minutes to allow the juices to redistribute.

Slice the steak against the grain into thin strips for maximum tenderness. Serve as desired, such as in tacos, over salads, or alongside grilled vegetables.