In a small bowl, whisk together the coconut aminos, toasted sesame oil, rice vinegar, and arrowroot powder to create the stir-fry sauce.
Thinly slice the flank steak against the grain into bite-sized strips and season evenly with sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips in a single layer and sear for 2-3 minutes until browned and caramelized, then transfer to a plate.
In the same skillet, add the broccoli florets, minced garlic, and grated ginger with a tablespoon of water.
Cover the pan for 2 minutes to steam the broccoli until it reaches a vibrant green and tender-crisp texture.
Return the beef to the skillet and pour the prepared sauce over the mixture.
Toss constantly for 1 minute until the glaze thickens and beautifully coats the beef and broccoli.
Sprinkle with sesame seeds before serving hot.