Slice the flank steak against the grain into thin, bite-sized strips.
In a small bowl, whisk together the coconut aminos, fresh grated ginger, and minced garlic to create the stir-fry sauce.
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, and sear until browned, about 2 minutes per side.
Remove the beef from the skillet and set aside on a plate.
Add the broccoli florets and sliced red bell pepper to the same skillet with a splash of water, covering for 2 minutes to steam-tenderize.
Return the beef to the skillet and pour the sauce over the mixture, tossing constantly for 1-2 minutes until the sauce thickens and coats everything.
Garnish with sesame seeds before serving hot.