Slice the flank steak against the grain into thin, bite-sized strips and season with sea salt and black pepper.
Mince the garlic and grate the fresh ginger.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the beef strips to the pan in a single layer and sear until browned, about 2 minutes per side, then remove beef from the pan and set aside.
In the same pan, add the broccoli florets and a splash of water, covering with a lid for 2 minutes to steam until vibrant green and tender-crisp.
Remove the lid and add the garlic and ginger, sautéing for 30 seconds until fragrant.
Return the beef to the pan and pour in the coconut aminos and toasted sesame oil.
Toss everything together for 1 minute until the sauce coats the ingredients evenly.
Plate the stir-fry and garnish with toasted sesame seeds before serving.