Slice the flank steak against the grain into thin, bite-sized strips and season evenly with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, arrowroot starch, and minced fresh ginger to create a smooth stir-fry glaze.
Heat the toasted sesame oil in a large stainless steel skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips to the hot pan in a single layer and sear for 2-3 minutes until browned and caramelized, then remove the beef and set it aside on a plate.
Add the broccoli florets and minced garlic to the same skillet with 2 tablespoons of water, then cover with a lid to steam for 3 minutes until tender-crisp.
Return the cooked beef to the skillet and pour the prepared glaze over the mixture.
Toss everything together for 1 minute until the sauce thickens and coats the beef and broccoli beautifully.
Serve the stir-fry immediately over the warm cooked brown rice and garnish with a sprinkle of toasted sesame seeds.