Thinly slice the flank steak against the grain into bite-sized strips and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, water, and arrowroot powder to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips to the skillet in a single layer and sear for 2-3 minutes until browned, then remove and set aside.
In the same skillet, add the broccoli florets with a splash of water, covering for 2 minutes to steam-fry until vibrant green and tender-crisp.
Stir in the minced garlic and ginger, sautéing for 30 seconds until fragrant.
Return the beef to the skillet and pour the sauce over the mixture, tossing constantly for 1 minute until the glaze thickens and coats everything.
Garnish with sesame seeds before serving hot.