Slice the flank steak against the grain into thin, bite-sized strips to ensure tenderness.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, and arrowroot starch until the starch is fully dissolved.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips to the pan in a single layer, seasoning them with sea salt and black pepper.
Sear the beef for 2-3 minutes until browned and slightly caramelized, then remove from the pan and set aside.
Add the broccoli florets and a splash of water to the same pan, covering with a lid for 2 minutes to steam-tenderize the vegetables.
Remove the lid and add the minced garlic and grated ginger, sautéing for 30 seconds until fragrant.
Return the beef to the pan and pour the prepared sauce over the mixture, tossing constantly for 1 minute until the glaze thickens and coats every piece.
Garnish with sesame seeds and serve immediately.