Thinly slice the flank steak against the grain into bite-sized strips and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos and sesame oil to create the stir-fry sauce.
Heat the avocado oil in a large skillet over medium-high heat until it begins to shimmer.
Add the steak strips to the pan and sear for 2-3 minutes until browned, then remove the beef and set it aside.
Add the broccoli to the same pan with a splash of water, covering with a lid for 2 minutes to steam until tender-crisp.
Stir in the minced garlic and grated ginger, sautéing for 30 seconds until the aromatics are fragrant.
Return the beef to the pan, pour in the sauce, and toss everything together for 1 minute until well coated.
Transfer the stir-fry to a plate and garnish with sesame seeds before serving hot.