Slice the flank steak against the grain into thin, bite-sized strips and season evenly with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, beef broth, grated fresh ginger, minced garlic, and arrowroot powder to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips in a single layer and sear for about 2 minutes until browned and caramelized, then remove the beef from the pan and set aside.
Add the broccoli florets to the same pan with a tablespoon of water; cover and steam for 2-3 minutes until bright green and tender-crisp.
Return the beef to the skillet and pour the prepared sauce over the mixture, tossing constantly for 1 minute until the glaze thickens and coats every piece.
Remove from heat, drizzle with toasted sesame oil, and garnish with sesame seeds before serving immediately.