Slice the flank steak against the grain into thin, bite-sized strips and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, and freshly grated ginger to create the stir-fry sauce.
Heat the avocado oil in a large cast-iron skillet or wok over medium-high heat until shimmering.
Add the beef strips in a single layer and sear for 2 minutes until browned and caramelized, then remove the beef from the pan and set aside.
Add the broccoli florets and sliced red bell pepper to the hot pan with a tablespoon of water; cover for 1 minute to lightly steam until vibrant and crisp-tender.
Remove the lid, add the minced garlic, and sauté for 30 seconds until fragrant.
Return the beef to the pan and pour the prepared sauce over the mixture, tossing constantly for 1 minute until the sauce thickens and glazes the ingredients.
Transfer to a plate and garnish with sesame seeds before serving hot.