Slice the flank steak against the grain into 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 grated fresh ginger to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips to the hot pan in a single layer and sear for 2 minutes until browned, then remove the beef and set it aside on a plate.
In the same pan, add the broccoli florets and sliced red bell peppers with a tablespoon of water, covering with a lid for 2 minutes to steam-tenderize.
Remove the lid, add the minced garlic, and sauté for 1 minute until the aroma is released.
Return the cooked beef to the pan and pour the sesame-ginger sauce over the ingredients, tossing constantly for 1-2 minutes until the sauce coats everything and thickens.
Transfer to a plate and garnish with sesame seeds before serving immediately.