Slice the beef flank steak against the grain into thin, bite-sized strips.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, minced ginger, minced garlic, and arrowroot powder to create a smooth glaze.
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 skillet and sear for 2-3 minutes, stirring occasionally until the meat is browned and just cooked through.
Toss in the broccoli florets along with one tablespoon of water, then cover the pan for 2 minutes to lightly steam the broccoli until it is tender-crisp.
Remove the lid and pour the prepared sesame-ginger glaze over the beef and broccoli, tossing continuously for 1 minute until the sauce thickens and coats everything.
Season with sea salt and black pepper, then serve immediately garnished with a sprinkle of sesame seeds.