Slice the flank steak against the grain into thin strips and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, water, and arrowroot starch to create the stir-fry glaze.
Heat a large skillet or wok over medium-high heat and add the toasted sesame oil.
Add the beef strips to the hot skillet 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-tenderize.
Stir in the minced garlic and grated ginger, sautéing for 30 seconds until fragrant.
Return the beef to the skillet and pour the sauce over the mixture, tossing constantly until the glaze thickens and becomes glossy.
Serve immediately topped with a sprinkle of sesame seeds for a nutty finish.