Slice the flank steak against the grain into thin, bite-sized strips.
In a small mixing bowl, whisk together the coconut aminos, minced fresh ginger, minced garlic, and arrowroot powder until smooth.
Place a large skillet or wok over medium-high heat and add the sesame oil.
Add the beef strips to the hot pan in a single layer, seasoning with sea salt and black pepper.
Sear the beef for 2-3 minutes until browned and caramelized, then remove from the pan and set aside.
Add the broccoli florets to the same pan with two tablespoons of water, covering with a lid for 2 minutes to steam until tender-crisp.
Return the beef to the pan and pour the prepared sauce over the ingredients.
Toss everything together for 1 minute until the sauce thickens and glossily coats the beef and broccoli.
Garnish with sesame seeds and serve immediately.