Slice the flank steak against the grain into thin, bite-sized strips.
In a small bowl, whisk together the coconut aminos, minced ginger, minced garlic, and red pepper flakes.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips to the skillet in a single layer, seasoning with sea salt and black pepper.
Sear the beef for 2-3 minutes until browned and just cooked through, then remove from the pan and set aside.
Add the broccoli florets to the same skillet with a splash of water, covering with a lid for 2 minutes to steam until bright green.
Return the beef to the skillet and pour the sauce over the mixture, tossing for 1 minute until the sauce thickens and coats everything.
Garnish with sesame seeds before serving.