Slice the flank steak against the grain into very thin strips and season evenly with sea salt and black pepper.
In a small glass bowl, whisk together the coconut aminos, toasted sesame oil, and freshly grated ginger to create the stir-fry sauce.
Heat the avocado oil in a large stainless steel skillet or wok over high heat until it begins to shimmer.
Add the beef strips in a single layer and sear without moving for 90 seconds to develop a deep brown crust, then toss and cook for 1 more minute.
Remove the beef from the pan and set aside on a plate.
Add the broccoli florets to the same pan with two tablespoons of water; cover immediately with a lid to steam for 2 minutes until tender-crisp.
Remove the lid, add the minced garlic, and sauté for 30 seconds until fragrant.
Return the beef and its juices to the pan, pour the sauce over the top, and toss everything together for 1 minute until the sauce glazes the ingredients.
Transfer to a plate and garnish with toasted sesame seeds before serving.