Thinly slice the flank steak against the grain into bite-sized strips.
Whisk together the coconut aminos, toasted sesame oil, minced ginger, and minced garlic in a small bowl.
Heat avocado 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, then remove from the pan and set aside.
Add the broccoli florets and sliced red bell pepper to the same skillet with a splash of water, covering for 2 minutes to steam-fry.
Return the beef to the skillet and pour the sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce coats the ingredients.
Garnish with sesame seeds before serving.