Slice the flank steak against the grain into thin strips and season with the sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, minced garlic, and grated fresh ginger to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips in a single layer and sear for 2 minutes until browned, then remove from the pan and set aside.
Add the broccoli florets to the same pan with two tablespoons of water, cover, and steam for 3 minutes until tender-crisp.
Return the beef to the pan, pour the sauce over the mixture, and toss for 1 minute until the sauce thickens and coats everything.
Transfer to a plate and garnish with sesame seeds before serving.