Thinly slice the flank steak against the grain into bite-sized strips.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, arrowroot powder, minced ginger, and minced garlic to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips to the pan in a single layer, seasoning with sea salt and black pepper, and sear until browned, about 2 minutes per side.
Remove the beef from the pan and add the broccoli florets with a splash of water, covering for 2 minutes to steam-soften.
Return the beef to the pan, pour the sauce over the mixture, and toss constantly for 1 minute until the glaze is thick and glossy.
Garnish with sesame seeds before serving.